640357690 has 16 divisors (see below), whose sum is σ = 1317307392. Its totient is φ = 219551184.

The previous prime is 640357667. The next prime is 640357771. The reversal of 640357690 is 96753046.

It is a super-2 number, since 2×640357690² = 820115942284272200, which contains 22 as substring.

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, 4573914 + ... + 4574053.

It is an arithmetic number, because the mean of its divisors is an integer number (82331712).

Almost surely, 2^640357690 is an apocalyptic number.

640357690 is an abundant number, since it is smaller than the sum of its proper divisors (676949702).

640357690 is a wasteful number, since it uses less digits than its factorization.

640357690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9147981.

The product of its (nonzero) digits is 136080, while the sum is 40.

The square root of 640357690 is about 25305.2897632096. The cubic root of 640357690 is about 861.9343918929.

The spelling of 640357690 in words is "six hundred forty million, three hundred fifty-seven thousand, six hundred ninety".