640967402 has 4 divisors (see below), whose sum is σ = 961451106. Its totient is φ = 320483700.

The previous prime is 640967399. The next prime is 640967407. The reversal of 640967402 is 204769046.

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., 638623441 + 2343961 = 25271^2 + 1531^2 .

It is not an unprimeable number, because it can be changed into a prime (640967407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160241849 + ... + 160241852.

Almost surely, 2^640967402 is an apocalyptic number.

640967402 is a deficient number, since it is larger than the sum of its proper divisors (320483704).

640967402 is a wasteful number, since it uses less digits than its factorization.

640967402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320483703.

The product of its (nonzero) digits is 72576, while the sum is 38.

The square root of 640967402 is about 25317.3340223650. The cubic root of 640967402 is about 862.2078666735.

The spelling of 640967402 in words is "six hundred forty million, nine hundred sixty-seven thousand, four hundred two".