16307815721 has 2 divisors, whose sum is σ = 16307815722. Its totient is φ = 16307815720.

The previous prime is 16307815703. The next prime is 16307815757. The reversal of 16307815721 is 12751870361.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14850103321 + 1457712400 = 121861^2 + 38180^2 .

It is a cyclic number.

It is not a de Polignac number, because 16307815721 - 2²⁶ = 16240706857 is a prime.

It is not a weakly prime, because it can be changed into another prime (16367815721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8153907860 + 8153907861.

It is an arithmetic number, because the mean of its divisors is an integer number (8153907861).

Almost surely, 2^16307815721 is an apocalyptic number.

It is an amenable number.

16307815721 is a deficient number, since it is larger than the sum of its proper divisors (1).

16307815721 is an equidigital number, since it uses as much as digits as its factorization.

16307815721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 70560, while the sum is 41.

The spelling of 16307815721 in words is "sixteen billion, three hundred seven million, eight hundred fifteen thousand, seven hundred twenty-one".