638634475 has 6 divisors (see below), whose sum is σ = 791906780. Its totient is φ = 510907560.

The previous prime is 638634473. The next prime is 638634481. The reversal of 638634475 is 574436836.

It is not a de Polignac number, because 638634475 - 2¹ = 638634473 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638634473) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12772665 + ... + 12772714.

Almost surely, 2^638634475 is an apocalyptic number.

638634475 is a deficient number, since it is larger than the sum of its proper divisors (153272305).

638634475 is a wasteful number, since it uses less digits than its factorization.

638634475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25545389 (or 25545384 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 46.

The square root of 638634475 is about 25271.2183125389. The cubic root of 638634475 is about 861.1605365857.

The spelling of 638634475 in words is "six hundred thirty-eight million, six hundred thirty-four thousand, four hundred seventy-five".