640977642 has 12 divisors (see below), whose sum is σ = 1388784930. Its totient is φ = 213659208.

The previous prime is 640977619. The next prime is 640977671. The reversal of 640977642 is 246779046.

It can be written as a sum of positive squares in only one way, i.e., 633075921 + 7901721 = 25161^2 + 2811^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17804917 + ... + 17804952.

Almost surely, 2^640977642 is an apocalyptic number.

640977642 is an abundant number, since it is smaller than the sum of its proper divisors (747807288).

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

640977642 is a wasteful number, since it uses less digits than its factorization.

640977642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35609877 (or 35609874 counting only the distinct ones).

The product of its (nonzero) digits is 508032, while the sum is 45.

The square root of 640977642 is about 25317.5362545410. The cubic root of 640977642 is about 862.2124581507.

The spelling of 640977642 in words is "six hundred forty million, nine hundred seventy-seven thousand, six hundred forty-two".