21688457490 has 48 divisors (see below), whose sum is σ = 64445704128. Its totient is φ = 4957361568.

The previous prime is 21688457477. The next prime is 21688457513. The reversal of 21688457490 is 9475488612.

It is a happy number.

21688457490 is a `hidden beast` number, since 2 + 1 + 68 + 8 + 4 + 574 + 9 + 0 = 666.

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, 17212432 + ... + 17213691.

It is an arithmetic number, because the mean of its divisors is an integer number (1342618836).

Almost surely, 2^21688457490 is an apocalyptic number.

21688457490 is an abundant number, since it is smaller than the sum of its proper divisors (42757246638).

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

21688457490 is a wasteful number, since it uses less digits than its factorization.

21688457490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34426143 (or 34426140 counting only the distinct ones).

The product of its (nonzero) digits is 3870720, while the sum is 54.

The spelling of 21688457490 in words is "twenty-one billion, six hundred eighty-eight million, four hundred fifty-seven thousand, four hundred ninety".