642664043666 has 32 divisors (see below), whose sum is σ = 1011519774720. Its totient is φ = 305650222416.

The previous prime is 642664043657. The next prime is 642664043711. The reversal of 642664043666 is 666340466246.

It is a super-2 number, since 2×642664043666² (a number of 24 digits) contains 22 as substring.

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, 7952435 + ... + 8032841.

It is an arithmetic number, because the mean of its divisors is an integer number (31609992960).

Almost surely, 2^642664043666 is an apocalyptic number.

642664043666 is a deficient number, since it is larger than the sum of its proper divisors (368855731054).

642664043666 is a wasteful number, since it uses less digits than its factorization.

642664043666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81398.

The product of its (nonzero) digits is 17915904, while the sum is 53.

The spelling of 642664043666 in words is "six hundred forty-two billion, six hundred sixty-four million, forty-three thousand, six hundred sixty-six".