640491475 has 12 divisors (see below), whose sum is σ = 855302896. Its totient is φ = 472978080.

The previous prime is 640491461. The next prime is 640491581. The reversal of 640491475 is 574194046.

It is not a de Polignac number, because 640491475 - 2⁵ = 640491443 is a prime.

It is a super-3 number, since 3×640491475³ (a number of 27 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 985047 + ... + 985696.

Almost surely, 2^640491475 is an apocalyptic number.

640491475 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

640491475 is a deficient number, since it is larger than the sum of its proper divisors (214811421).

640491475 is a wasteful number, since it uses less digits than its factorization.

640491475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1970766 (or 1970761 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 40.

The square root of 640491475 is about 25307.9330447984. The cubic root of 640491475 is about 861.9944134844.

It can be divided in two parts, 6404 and 91475, that added together give a palindrome (97879).

The spelling of 640491475 in words is "six hundred forty million, four hundred ninety-one thousand, four hundred seventy-five".