20315917 has 2 divisors, whose sum is σ = 20315918. Its totient is φ = 20315916.

The previous prime is 20315887. The next prime is 20316017. The reversal of 20315917 is 71951302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20304036 + 11881 = 4506^2 + 109^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20315917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20315117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10157958 + 10157959.

It is an arithmetic number, because the mean of its divisors is an integer number (10157959).

Almost surely, 2^20315917 is an apocalyptic number.

It is an amenable number.

20315917 is a deficient number, since it is larger than the sum of its proper divisors (1).

20315917 is an equidigital number, since it uses as much as digits as its factorization.

20315917 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 20315917 is about 4507.3181605030. The cubic root of 20315917 is about 272.8635195566.

The spelling of 20315917 in words is "twenty million, three hundred fifteen thousand, nine hundred seventeen".