640207628 has 12 divisors (see below), whose sum is σ = 1124828712. Its totient is φ = 318828000.

The previous prime is 640207621. The next prime is 640207649. The reversal of 640207628 is 826702046.

It is not an unprimeable number, because it can be changed into a prime (640207621) 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, 317825 + ... + 319832.

It is an arithmetic number, because the mean of its divisors is an integer number (93735726).

Almost surely, 2^640207628 is an apocalyptic number.

It is an amenable number.

640207628 is a deficient number, since it is larger than the sum of its proper divisors (484621084).

640207628 is a wasteful number, since it uses less digits than its factorization.

640207628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 637912 (or 637910 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 640207628 is about 25302.3245572418. The cubic root of 640207628 is about 861.8670578047.

The spelling of 640207628 in words is "six hundred forty million, two hundred seven thousand, six hundred twenty-eight".