15965921281 has 2 divisors, whose sum is σ = 15965921282. Its totient is φ = 15965921280.

The previous prime is 15965921269. The next prime is 15965921357. The reversal of 15965921281 is 18212956951.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15916345600 + 49575681 = 126160^2 + 7041^2 .

It is a cyclic number.

It is not a de Polignac number, because 15965921281 - 2¹⁵ = 15965888513 is a prime.

It is a super-2 number, since 2×15965921281² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (15965921221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7982960640 + 7982960641.

It is an arithmetic number, because the mean of its divisors is an integer number (7982960641).

Almost surely, 2^15965921281 is an apocalyptic number.

It is an amenable number.

15965921281 is a deficient number, since it is larger than the sum of its proper divisors (1).

15965921281 is an equidigital number, since it uses as much as digits as its factorization.

15965921281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 388800, while the sum is 49.

The spelling of 15965921281 in words is "fifteen billion, nine hundred sixty-five million, nine hundred twenty-one thousand, two hundred eighty-one".