21640662426 has 16 divisors (see below), whose sum is σ = 43322053824. Its totient is φ = 7206765984.

The previous prime is 21640662419. The next prime is 21640662443. The reversal of 21640662426 is 62426604612.

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, 1690131 + ... + 1702886.

It is an arithmetic number, because the mean of its divisors is an integer number (2707628364).

Almost surely, 2^21640662426 is an apocalyptic number.

21640662426 is an abundant number, since it is smaller than the sum of its proper divisors (21681391398).

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

21640662426 is a wasteful number, since it uses less digits than its factorization.

21640662426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3394085.

The product of its (nonzero) digits is 165888, while the sum is 39.

The spelling of 21640662426 in words is "twenty-one billion, six hundred forty million, six hundred sixty-two thousand, four hundred twenty-six".