21631260 has 48 divisors (see below), whose sum is σ = 69221376. Its totient is φ = 4944192.

The previous prime is 21631243. The next prime is 21631283. The reversal of 21631260 is 6213612.

It is a happy number.

It is a super-2 number, since 2×21631260² = 935822818375200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25332 + ... + 26171.

It is an arithmetic number, because the mean of its divisors is an integer number (1442112).

Almost surely, 2^21631260 is an apocalyptic number.

21631260 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21631260 is an abundant number, since it is smaller than the sum of its proper divisors (47590116).

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

21631260 is a wasteful number, since it uses less digits than its factorization.

21631260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51522 (or 51520 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21631260 is about 4650.9418401008. The cubic root of 21631260 is about 278.6296134684.

Adding to 21631260 its reverse (6213612), we get a palindrome (27844872).

The spelling of 21631260 in words is "twenty-one million, six hundred thirty-one thousand, two hundred sixty".