638657402 has 8 divisors (see below), whose sum is σ = 958468512. Its totient is φ = 319167900.

The previous prime is 638657389. The next prime is 638657419. The reversal of 638657402 is 204756836.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 638657402.

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 3 ways as a sum of consecutive naturals, for example, 75374 + ... + 83417.

It is an arithmetic number, because the mean of its divisors is an integer number (119808564).

Almost surely, 2^638657402 is an apocalyptic number.

638657402 is a deficient number, since it is larger than the sum of its proper divisors (319811110).

638657402 is a wasteful number, since it uses less digits than its factorization.

638657402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160804.

The product of its (nonzero) digits is 241920, while the sum is 41.

The square root of 638657402 is about 25271.6719272786. The cubic root of 638657402 is about 861.1708416935.

The spelling of 638657402 in words is "six hundred thirty-eight million, six hundred fifty-seven thousand, four hundred two".