20164506721 has 2 divisors, whose sum is σ = 20164506722. Its totient is φ = 20164506720.

The previous prime is 20164506707. The next prime is 20164506737. The reversal of 20164506721 is 12760546102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12619152225 + 7545354496 = 112335^2 + 86864^2 .

It is a cyclic number.

It is not a de Polignac number, because 20164506721 - 2⁵ = 20164506689 is a prime.

It is not a weakly prime, because it can be changed into another prime (20164506821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10082253360 + 10082253361.

It is an arithmetic number, because the mean of its divisors is an integer number (10082253361).

Almost surely, 2^20164506721 is an apocalyptic number.

It is an amenable number.

20164506721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20164506721 is an equidigital number, since it uses as much as digits as its factorization.

20164506721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 34.

The spelling of 20164506721 in words is "twenty billion, one hundred sixty-four million, five hundred six thousand, seven hundred twenty-one".