638996679 has 6 divisors (see below), whose sum is σ = 922995216. Its totient is φ = 425997780.

The previous prime is 638996671. The next prime is 638996711. The reversal of 638996679 is 976699836.

It is not a de Polignac number, because 638996679 - 2³ = 638996671 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638996671) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 35499807 + ... + 35499824.

It is an arithmetic number, because the mean of its divisors is an integer number (153832536).

Almost surely, 2^638996679 is an apocalyptic number.

638996679 is a deficient number, since it is larger than the sum of its proper divisors (283998537).

638996679 is a wasteful number, since it uses less digits than its factorization.

638996679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70999637 (or 70999634 counting only the distinct ones).

The product of its digits is 26453952, while the sum is 63.

The square root of 638996679 is about 25278.3836310789. The cubic root of 638996679 is about 861.3233093212.

The spelling of 638996679 in words is "six hundred thirty-eight million, nine hundred ninety-six thousand, six hundred seventy-nine".