638407378677 has 4 divisors (see below), whose sum is σ = 851209838240. Its totient is φ = 425604919116.

The previous prime is 638407378643. The next prime is 638407378703. The reversal of 638407378677 is 776873704836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 638407378677 - 2⁶ = 638407378613 is a prime.

It is a super-2 number, since 2×638407378677² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638407378607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106401229777 + ... + 106401229782.

It is an arithmetic number, because the mean of its divisors is an integer number (212802459560).

Almost surely, 2^638407378677 is an apocalyptic number.

It is an amenable number.

638407378677 is a deficient number, since it is larger than the sum of its proper divisors (212802459563).

638407378677 is a wasteful number, since it uses less digits than its factorization.

638407378677 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212802459562.

The product of its (nonzero) digits is 199148544, while the sum is 66.

The spelling of 638407378677 in words is "six hundred thirty-eight billion, four hundred seven million, three hundred seventy-eight thousand, six hundred seventy-seven".