640621623666 has 16 divisors (see below), whose sum is σ = 1283693049504. Its totient is φ = 213132240864.

The previous prime is 640621623637. The next prime is 640621623689. The reversal of 640621623666 is 666326126046.

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, 102071691 + ... + 102077966.

It is an arithmetic number, because the mean of its divisors is an integer number (80230815594).

Almost surely, 2^640621623666 is an apocalyptic number.

640621623666 is an abundant number, since it is smaller than the sum of its proper divisors (643071425838).

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

640621623666 is a wasteful number, since it uses less digits than its factorization.

640621623666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204150185.

The product of its (nonzero) digits is 2239488, while the sum is 48.

The spelling of 640621623666 in words is "six hundred forty billion, six hundred twenty-one million, six hundred twenty-three thousand, six hundred sixty-six".