21631530 has 16 divisors (see below), whose sum is σ = 51915744. Its totient is φ = 5768400.

The previous prime is 21631517. The next prime is 21631541. The reversal of 21631530 is 3513612.

It is a junction number, because it is equal to n+sod(n) for n = 21631497 and 21631506.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 360496 + ... + 360555.

It is an arithmetic number, because the mean of its divisors is an integer number (3244734).

Almost surely, 2^21631530 is an apocalyptic number.

21631530 is an abundant number, since it is smaller than the sum of its proper divisors (30284214).

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

21631530 is a wasteful number, since it uses less digits than its factorization.

21631530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721061.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21631530 is about 4650.9708663891. The cubic root of 21631530 is about 278.6307727425.

The spelling of 21631530 in words is "twenty-one million, six hundred thirty-one thousand, five hundred thirty".