638974811 has 4 divisors (see below), whose sum is σ = 639210000. Its totient is φ = 638739624.

The previous prime is 638974781. The next prime is 638974813. The reversal of 638974811 is 118479836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638974811 - 2⁶ = 638974747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638974813) 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, 113471 + ... + 118968.

It is an arithmetic number, because the mean of its divisors is an integer number (159802500).

Almost surely, 2^638974811 is an apocalyptic number.

638974811 is a deficient number, since it is larger than the sum of its proper divisors (235189).

638974811 is a wasteful number, since it uses less digits than its factorization.

638974811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235188.

The product of its digits is 290304, while the sum is 47.

The square root of 638974811 is about 25277.9510838992. The cubic root of 638974811 is about 861.3134836922.

The spelling of 638974811 in words is "six hundred thirty-eight million, nine hundred seventy-four thousand, eight hundred eleven".