The Number

21

Twenty-One

In Base 15 Quindecimal Is

1615

The numbers with a 15 subscript use Base 15 Quindecimal notation.

For more familiar numbers: See Twenty-One in Base 10 Decimal

Nearby Numbers

Positive, nonzero integers within three units

18
1315
Eightteen in Base 15 Quindecimal
19
1415
Nineteen in Base 15 Quindecimal
20
1515
Twenty in Base 15 Quindecimal
22
1715
Twenty-Two in Base 15 Quindecimal
23
1815
Twenty-Three in Base 15 Quindecimal
24
1915
Twenty-Four in Base 15 Quindecimal

Scientific Notation

Scientific notation expresses a quantity as the product of its significand with 10 raised to an integer exponent.

2.1e1

Reciprocal

A number multiplied with its reciprocal is one.

0.0aaaaaaaaaaaaa915

The reciprocal of 21 in Base 15 Quindecimal.

Palindrome?

A numerical palindrome has the same value when all of its digits are reversed.

The number 1615 is not a palindrome.

Not A Prime Number

A prime number is a positive integer that is divisible only by itself and one.

Twenty-one is a composite number with 4 total factors (including 1 and itself).   See primes in Base 15 Quindecimal

A Composite

Composites have more than just these two factors.

Twenty-one is a composite number with 4 total factors (including 1 and itself).

Prime Factors

The prime factors of a positive integer are the integers that divide it exactly and are also prime.

The number twenty-one has the following 2 prime factors:

3
315
Three in Base 15 Quindecimal
7
715
Seven in Base 15 Quindecimal

Prime Factorization

The prime factorization of a positive integer is the unique list of prime factors together with their multiplicities

3151 · 7151 = 1615

Base Conversions

The number twenty-one in 35 different bases