21315991576 has 32 divisors (see below), whose sum is σ = 44251663680. Its totient is φ = 9544471200.

The previous prime is 21315991573. The next prime is 21315991621. The reversal of 21315991576 is 67519951312.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315991573) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1801770 + ... + 1813561.

It is an arithmetic number, because the mean of its divisors is an integer number (1382864490).

Almost surely, 2^21315991576 is an apocalyptic number.

It is an amenable number.

21315991576 is an abundant number, since it is smaller than the sum of its proper divisors (22935672104).

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

21315991576 is a wasteful number, since it uses less digits than its factorization.

21315991576 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3615415 (or 3615411 counting only the distinct ones).

The product of its digits is 510300, while the sum is 49.

The spelling of 21315991576 in words is "twenty-one billion, three hundred fifteen million, nine hundred ninety-one thousand, five hundred seventy-six".