638739690 has 32 divisors (see below), whose sum is σ = 1537548480. Its totient is φ = 169822464.

The previous prime is 638739677. The next prime is 638739709. The reversal of 638739690 is 96937836.

It is a happy number.

It is a super-2 number, since 2×638739690² = 815976783162592200, which contains 22 as substring.

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 15 ways as a sum of consecutive naturals, for example, 21480 + ... + 41699.

It is an arithmetic number, because the mean of its divisors is an integer number (48048390).

Almost surely, 2^638739690 is an apocalyptic number.

638739690 is an abundant number, since it is smaller than the sum of its proper divisors (898808790).

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

638739690 is a wasteful number, since it uses less digits than its factorization.

638739690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63526.

The product of its (nonzero) digits is 1469664, while the sum is 51.

The square root of 638739690 is about 25273.2999428250. The cubic root of 638739690 is about 861.2078260416.

The spelling of 638739690 in words is "six hundred thirty-eight million, seven hundred thirty-nine thousand, six hundred ninety".