640085408 has 12 divisors (see below), whose sum is σ = 1260168210. Its totient is φ = 320042688.

The previous prime is 640085359. The next prime is 640085429. The reversal of 640085408 is 804580046.

It can be written as a sum of positive squares in only one way, i.e., 442176784 + 197908624 = 21028^2 + 14068^2 .

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10001303 + ... + 10001366.

Almost surely, 2^640085408 is an apocalyptic number.

It is an amenable number.

640085408 is a deficient number, since it is larger than the sum of its proper divisors (620082802).

640085408 is a wasteful number, since it uses less digits than its factorization.

640085408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20002679 (or 20002671 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 35.

The square root of 640085408 is about 25299.9092488491. The cubic root of 640085408 is about 861.8122088822.

The spelling of 640085408 in words is "six hundred forty million, eighty-five thousand, four hundred eight".