640378194 has 16 divisors (see below), whose sum is σ = 1288915968. Its totient is φ = 212099472.

The previous prime is 640378169. The next prime is 640378217. The reversal of 640378194 is 491873046.

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, 338962 + ... + 340845.

It is an arithmetic number, because the mean of its divisors is an integer number (80557248).

Almost surely, 2^640378194 is an apocalyptic number.

640378194 is an abundant number, since it is smaller than the sum of its proper divisors (648537774).

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

640378194 is a wasteful number, since it uses less digits than its factorization.

640378194 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 679969.

The product of its (nonzero) digits is 145152, while the sum is 42.

The square root of 640378194 is about 25305.6948926521. The cubic root of 640378194 is about 861.9435913942.

The spelling of 640378194 in words is "six hundred forty million, three hundred seventy-eight thousand, one hundred ninety-four".