20900720617913 has 2 divisors, whose sum is σ = 20900720617914. Its totient is φ = 20900720617912.

The previous prime is 20900720617837. The next prime is 20900720618003. The reversal of 20900720617913 is 31971602700902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18589308187024 + 2311412430889 = 4311532^2 + 1520333^2 .

It is a cyclic number.

It is not a de Polignac number, because 20900720617913 - 2²⁰ = 20900719569337 is a prime.

It is not a weakly prime, because it can be changed into another prime (20900720617013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10450360308956 + 10450360308957.

It is an arithmetic number, because the mean of its divisors is an integer number (10450360308957).

Almost surely, 2^{20900720617913} is an apocalyptic number.

It is an amenable number.

20900720617913 is a deficient number, since it is larger than the sum of its proper divisors (1).

20900720617913 is an equidigital number, since it uses as much as digits as its factorization.

20900720617913 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 285768, while the sum is 47.

The spelling of 20900720617913 in words is "twenty trillion, nine hundred billion, seven hundred twenty million, six hundred seventeen thousand, nine hundred thirteen".