Nearby Numbers

Positive, nonzero integers within three units

21006

Twenty-One Thousand and Six

21007

Twenty-One Thousand and Seven

21008

Twenty-One Thousand and Eight

21010

Twenty-One Thousand and Ten

21011

Twenty-One Thousand and Eleven

21012

Twenty-One Thousand and Twelve

Scientific Notation

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

2.1009e4

Reciprocal

A number multiplied with its reciprocal is one.

0.00004759864819839116

The reciprocal of 21009.

Palindrome?

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

The number 21009 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 thousand and nine is a composite number with 8 total factors (including 1 and itself).   See primes in Base 10 Decimal

A Composite

Composites have more than just these two factors.

Twenty-one thousand and nine is a composite number with 8 total factors (including 1 and itself).

Prime Factors

3

Three

47

Forty-Seven

149

One Hundred and Forty-Nine

Prime Factorization

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

31 · 471 · 1491 = 21009

Base Conversions

The number twenty-one thousand and nine in 35 different bases