636739121 has 2 divisors, whose sum is σ = 636739122. Its totient is φ = 636739120.

The previous prime is 636739027. The next prime is 636739171. The reversal of 636739121 is 121937636.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 452838400 + 183900721 = 21280^2 + 13561^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-636739121 is a prime.

It is not a weakly prime, because it can be changed into another prime (636739171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318369560 + 318369561.

It is an arithmetic number, because the mean of its divisors is an integer number (318369561).

Almost surely, 2^636739121 is an apocalyptic number.

It is an amenable number.

636739121 is a deficient number, since it is larger than the sum of its proper divisors (1).

636739121 is an equidigital number, since it uses as much as digits as its factorization.

636739121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 38.

The square root of 636739121 is about 25233.6901978288. The cubic root of 636739121 is about 860.3077684287.

The spelling of 636739121 in words is "six hundred thirty-six million, seven hundred thirty-nine thousand, one hundred twenty-one".