21531632238 has 48 divisors (see below), whose sum is σ = 49122337680. Its totient is φ = 6797371392.

The previous prime is 21531632209. The next prime is 21531632261. The reversal of 21531632238 is 83223613512.

21531632238 is a `hidden beast` number, since 2 + 15 + 3 + 1 + 632 + 2 + 3 + 8 = 666.

It is a super-2 number, since 2×21531632238² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1405870 + ... + 1421102.

It is an arithmetic number, because the mean of its divisors is an integer number (1023382035).

Almost surely, 2^21531632238 is an apocalyptic number.

21531632238 is an abundant number, since it is smaller than the sum of its proper divisors (27590705442).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21531632238 is a wasteful number, since it uses less digits than its factorization.

21531632238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19393 (or 19390 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The spelling of 21531632238 in words is "twenty-one billion, five hundred thirty-one million, six hundred thirty-two thousand, two hundred thirty-eight".