642664043668 has 24 divisors (see below), whose sum is σ = 1163476840680. Its totient is φ = 310242723840.

The previous prime is 642664043657. The next prime is 642664043711. The reversal of 642664043668 is 866340466246.

It can be written as a sum of positive squares in 4 ways, for example, as 126016480144 + 516647563524 = 354988^2 + 718782^2 .

It is a congruent number.

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, 5968548 + ... + 6075268.

It is an arithmetic number, because the mean of its divisors is an integer number (48478201695).

Almost surely, 2^642664043668 is an apocalyptic number.

It is an amenable number.

642664043668 is a deficient number, since it is larger than the sum of its proper divisors (520812797012).

642664043668 is a wasteful number, since it uses less digits than its factorization.

642664043668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158667 (or 158665 counting only the distinct ones).

The product of its (nonzero) digits is 23887872, while the sum is 55.

The spelling of 642664043668 in words is "six hundred forty-two billion, six hundred sixty-four million, forty-three thousand, six hundred sixty-eight".