636939913 has 4 divisors (see below), whose sum is σ = 639721540. Its totient is φ = 634158288.

The previous prime is 636939881. The next prime is 636939923. The reversal of 636939913 is 319939636.

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 466689609 + 170250304 = 21603^2 + 13048^2 .

It is a cyclic number.

It is not a de Polignac number, because 636939913 - 2⁵ = 636939881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (636939923) 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, 1390470 + ... + 1390927.

It is an arithmetic number, because the mean of its divisors is an integer number (159930385).

Almost surely, 2^636939913 is an apocalyptic number.

It is an amenable number.

636939913 is a deficient number, since it is larger than the sum of its proper divisors (2781627).

636939913 is a wasteful number, since it uses less digits than its factorization.

636939913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2781626.

The product of its digits is 708588, while the sum is 49.

The square root of 636939913 is about 25237.6685333650. The cubic root of 636939913 is about 860.3981899515.

The spelling of 636939913 in words is "six hundred thirty-six million, nine hundred thirty-nine thousand, nine hundred thirteen".