640449398 has 64 divisors (see below), whose sum is σ = 1134673920. Its totient is φ = 269068800.

The previous prime is 640449389. The next prime is 640449503. The reversal of 640449398 is 893944046.

It is a happy number.

It is a congruent 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 31 ways as a sum of consecutive naturals, for example, 702563 + ... + 703473.

It is an arithmetic number, because the mean of its divisors is an integer number (17729280).

Almost surely, 2^640449398 is an apocalyptic number.

640449398 is a deficient number, since it is larger than the sum of its proper divisors (494224522).

640449398 is a wasteful number, since it uses less digits than its factorization.

640449398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1013.

The product of its (nonzero) digits is 746496, while the sum is 47.

The square root of 640449398 is about 25307.1017305420. The cubic root of 640449398 is about 861.9755368693.

The spelling of 640449398 in words is "six hundred forty million, four hundred forty-nine thousand, three hundred ninety-eight".