638796913 has 4 divisors (see below), whose sum is σ = 676373220. Its totient is φ = 601220608.

The previous prime is 638796911. The next prime is 638796931. The reversal of 638796913 is 319697836.

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

It can be written as a sum of positive squares in 2 ways, for example, as 272151009 + 366645904 = 16497^2 + 19148^2 .

It is a cyclic number.

It is not a de Polignac number, because 638796913 - 2¹ = 638796911 is a prime.

It is a super-2 number, since 2×638796913² = 816122992116659138, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (638796911) 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, 18788128 + ... + 18788161.

It is an arithmetic number, because the mean of its divisors is an integer number (169093305).

Almost surely, 2^638796913 is an apocalyptic number.

It is an amenable number.

638796913 is a deficient number, since it is larger than the sum of its proper divisors (37576307).

638796913 is a wasteful number, since it uses less digits than its factorization.

638796913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37576306.

The product of its digits is 1469664, while the sum is 52.

The square root of 638796913 is about 25274.4320015307. The cubic root of 638796913 is about 861.2335430510.

The spelling of 638796913 in words is "six hundred thirty-eight million, seven hundred ninety-six thousand, nine hundred thirteen".