21038632209 has 27 divisors (see below), whose sum is σ = 35355745737. Its totient is φ = 12020334984.

The previous prime is 21038632187. The next prime is 21038632213. The reversal of 21038632209 is 90223683012.

The square root of 21038632209 is 145047.

It is a perfect power (a square), and thus also a powerful number.

21038632209 is a `hidden beast` number, since 2 + 10 + 3 + 8 + 632 + 2 + 0 + 9 = 666.

It is not a de Polignac number, because 21038632209 - 2⁵ = 21038632177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21038632249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 3042534 + ... + 3049440.

Almost surely, 2^21038632209 is an apocalyptic number.

21038632209 is the 145047-th square number.

21038632209 is the 72524-th centered octagonal number.

It is an amenable number.

21038632209 is a deficient number, since it is larger than the sum of its proper divisors (14317113528).

21038632209 is an frugal number, since it uses more digits than its factorization.

21038632209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13834 (or 6917 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

Multiplying 21038632209 by its sum of digits (36), we get a square (757390759524 = 870282²).

The spelling of 21038632209 in words is "twenty-one billion, thirty-eight million, six hundred thirty-two thousand, two hundred nine".