640664522 has 8 divisors (see below), whose sum is σ = 961401636. Its totient is φ = 320197312.

The previous prime is 640664503. The next prime is 640664527. The reversal of 640664522 is 225466046.

It can be written as a sum of positive squares in 2 ways, for example, as 560221561 + 80442961 = 23669^2 + 8969^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (640664527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61433 + ... + 71100.

Almost surely, 2^640664522 is an apocalyptic number.

640664522 is a deficient number, since it is larger than the sum of its proper divisors (320737114).

640664522 is a wasteful number, since it uses less digits than its factorization.

640664522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134952.

The product of its (nonzero) digits is 69120, while the sum is 35.

The square root of 640664522 is about 25311.3516430869. The cubic root of 640664522 is about 862.0720372683.

The spelling of 640664522 in words is "six hundred forty million, six hundred sixty-four thousand, five hundred twenty-two".