21612640231666 has 64 divisors (see below), whose sum is σ = 38241151885440. Its totient is φ = 9079878931200.

The previous prime is 21612640231607. The next prime is 21612640231717. The reversal of 21612640231666 is 66613204621612.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4440150 + ... + 7933486.

It is an arithmetic number, because the mean of its divisors is an integer number (597517998210).

Almost surely, 2^{21612640231666} is an apocalyptic number.

21612640231666 is a deficient number, since it is larger than the sum of its proper divisors (16628511653774).

21612640231666 is a wasteful number, since it uses less digits than its factorization.

21612640231666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3493448 (or 3493410 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 46.

The spelling of 21612640231666 in words is "twenty-one trillion, six hundred twelve billion, six hundred forty million, two hundred thirty-one thousand, six hundred sixty-six".