15216731221 has 2 divisors, whose sum is σ = 15216731222. Its totient is φ = 15216731220.

The previous prime is 15216731183. The next prime is 15216731281. The reversal of 15216731221 is 12213761251.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15184400625 + 32330596 = 123225^2 + 5686^2 .

It is a cyclic number.

It is not a de Polignac number, because 15216731221 - 2⁹ = 15216730709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15216731281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7608365610 + 7608365611.

It is an arithmetic number, because the mean of its divisors is an integer number (7608365611).

Almost surely, 2^15216731221 is an apocalyptic number.

It is an amenable number.

15216731221 is a deficient number, since it is larger than the sum of its proper divisors (1).

15216731221 is an equidigital number, since it uses as much as digits as its factorization.

15216731221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 31.

The spelling of 15216731221 in words is "fifteen billion, two hundred sixteen million, seven hundred thirty-one thousand, two hundred twenty-one".