20305507921 has 2 divisors, whose sum is σ = 20305507922. Its totient is φ = 20305507920.

The previous prime is 20305507889. The next prime is 20305508009. The reversal of 20305507921 is 12970550302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17966721600 + 2338786321 = 134040^2 + 48361^2 .

It is a cyclic number.

It is not a de Polignac number, because 20305507921 - 2⁵ = 20305507889 is a prime.

It is not a weakly prime, because it can be changed into another prime (20305508921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10152753960 + 10152753961.

It is an arithmetic number, because the mean of its divisors is an integer number (10152753961).

Almost surely, 2^20305507921 is an apocalyptic number.

It is an amenable number.

20305507921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20305507921 is an equidigital number, since it uses as much as digits as its factorization.

20305507921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18900, while the sum is 34.

The spelling of 20305507921 in words is "twenty billion, three hundred five million, five hundred seven thousand, nine hundred twenty-one".