640964920642 has 4 divisors (see below), whose sum is σ = 961447380966. Its totient is φ = 320482460320.

The previous prime is 640964920613. The next prime is 640964920643. The reversal of 640964920642 is 246029469046.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 634605017641 + 6359903001 = 796621^2 + 79749^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 640964920642.

It is not an unprimeable number, because it can be changed into a prime (640964920643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160241230159 + ... + 160241230162.

Almost surely, 2^640964920642 is an apocalyptic number.

640964920642 is a deficient number, since it is larger than the sum of its proper divisors (320482460324).

640964920642 is a wasteful number, since it uses less digits than its factorization.

640964920642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320482460323.

The product of its (nonzero) digits is 4478976, while the sum is 52.

The spelling of 640964920642 in words is "six hundred forty billion, nine hundred sixty-four million, nine hundred twenty thousand, six hundred forty-two".