15927120721 has 2 divisors, whose sum is σ = 15927120722. Its totient is φ = 15927120720.

The previous prime is 15927120689. The next prime is 15927120733. The reversal of 15927120721 is 12702172951.

It is a happy number.

15927120721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15114243600 + 812877121 = 122940^2 + 28511^2 .

It is a cyclic number.

It is not a de Polignac number, because 15927120721 - 2⁵ = 15927120689 is a prime.

It is a super-2 number, since 2×15927120721² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (15927120761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7963560360 + 7963560361.

It is an arithmetic number, because the mean of its divisors is an integer number (7963560361).

Almost surely, 2^15927120721 is an apocalyptic number.

It is an amenable number.

15927120721 is a deficient number, since it is larger than the sum of its proper divisors (1).

15927120721 is an equidigital number, since it uses as much as digits as its factorization.

15927120721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17640, while the sum is 37.

The spelling of 15927120721 in words is "fifteen billion, nine hundred twenty-seven million, one hundred twenty thousand, seven hundred twenty-one".