15965921381 has 2 divisors, whose sum is σ = 15965921382. Its totient is φ = 15965921380.

The previous prime is 15965921357. The next prime is 15965921401. The reversal of 15965921381 is 18312956951.

15965921381 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., 15063880225 + 902041156 = 122735^2 + 30034^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15965921381 is a prime.

It is a super-2 number, since 2×15965921381² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15965921281) 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, 7982960690 + 7982960691.

It is an arithmetic number, because the mean of its divisors is an integer number (7982960691).

Almost surely, 2^15965921381 is an apocalyptic number.

It is an amenable number.

15965921381 is a deficient number, since it is larger than the sum of its proper divisors (1).

15965921381 is an equidigital number, since it uses as much as digits as its factorization.

15965921381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 583200, while the sum is 50.

The spelling of 15965921381 in words is "fifteen billion, nine hundred sixty-five million, nine hundred twenty-one thousand, three hundred eighty-one".