640355478 has 32 divisors (see below), whose sum is σ = 1464739584. Its totient is φ = 182824992.

The previous prime is 640355459. The next prime is 640355479. The reversal of 640355478 is 874553046.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640355479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62301 + ... + 71847.

It is an arithmetic number, because the mean of its divisors is an integer number (45773112).

Almost surely, 2^640355478 is an apocalyptic number.

640355478 is an abundant number, since it is smaller than the sum of its proper divisors (824384106).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640355478 is a wasteful number, since it uses less digits than its factorization.

640355478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11156.

The product of its (nonzero) digits is 403200, while the sum is 42.

The square root of 640355478 is about 25305.2460568950. The cubic root of 640355478 is about 861.9333994262.

The spelling of 640355478 in words is "six hundred forty million, three hundred fifty-five thousand, four hundred seventy-eight".