640426402 has 16 divisors (see below), whose sum is σ = 1197680832. Its totient is φ = 249516720.

The previous prime is 640426349. The next prime is 640426403. The reversal of 640426402 is 204624046.

640426402 = 4769² + 4770² + ... + 4796².

It is not an unprimeable number, because it can be changed into a prime (640426403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2079153 + ... + 2079460.

It is an arithmetic number, because the mean of its divisors is an integer number (74855052).

Almost surely, 2^640426402 is an apocalyptic number.

640426402 is a deficient number, since it is larger than the sum of its proper divisors (557254430).

640426402 is a wasteful number, since it uses less digits than its factorization.

640426402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4158633.

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 640426402 is about 25306.6473875936. The cubic root of 640426402 is about 861.9652200372.

The spelling of 640426402 in words is "six hundred forty million, four hundred twenty-six thousand, four hundred two".