640449090 has 48 divisors (see below), whose sum is σ = 1671860736. Its totient is φ = 170100000.

The previous prime is 640449067. The next prime is 640449101. The reversal of 640449090 is 90944046.

640449090 is a `hidden beast` number, since 640 + 4 + 4 + 9 + 0 + 9 + 0 = 666.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 8415 + ... + 36765.

It is an arithmetic number, because the mean of its divisors is an integer number (34830432).

Almost surely, 2^640449090 is an apocalyptic number.

640449090 is an abundant number, since it is smaller than the sum of its proper divisors (1031411646).

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

640449090 is a wasteful number, since it uses less digits than its factorization.

640449090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28615 (or 28612 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 640449090 is about 25307.0956452928. The cubic root of 640449090 is about 861.9753986910.

The spelling of 640449090 in words is "six hundred forty million, four hundred forty-nine thousand, ninety".