20016796721 has 2 divisors, whose sum is σ = 20016796722. Its totient is φ = 20016796720.

The previous prime is 20016796717. The next prime is 20016796741. The reversal of 20016796721 is 12769761002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12686868496 + 7329928225 = 112636^2 + 85615^2 .

It is a cyclic number.

It is not a de Polignac number, because 20016796721 - 2² = 20016796717 is a prime.

It is not a weakly prime, because it can be changed into another prime (20016796741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10008398360 + 10008398361.

It is an arithmetic number, because the mean of its divisors is an integer number (10008398361).

Almost surely, 2^20016796721 is an apocalyptic number.

It is an amenable number.

20016796721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20016796721 is an equidigital number, since it uses as much as digits as its factorization.

20016796721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 63504, while the sum is 41.

The spelling of 20016796721 in words is "twenty billion, sixteen million, seven hundred ninety-six thousand, seven hundred twenty-one".