21023652666 has 32 divisors (see below), whose sum is σ = 42711251328. Its totient is φ = 6897623040.

The previous prime is 21023652647. The next prime is 21023652737. The reversal of 21023652666 is 66625632012.

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, 164026 + ... + 262586.

It is an arithmetic number, because the mean of its divisors is an integer number (1334726604).

Almost surely, 2^21023652666 is an apocalyptic number.

21023652666 is an abundant number, since it is smaller than the sum of its proper divisors (21687598662).

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

21023652666 is a wasteful number, since it uses less digits than its factorization.

21023652666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99126.

The product of its (nonzero) digits is 155520, while the sum is 39.

The spelling of 21023652666 in words is "twenty-one billion, twenty-three million, six hundred fifty-two thousand, six hundred sixty-six".