15958978561 has 2 divisors, whose sum is σ = 15958978562. Its totient is φ = 15958978560.

The previous prime is 15958978547. The next prime is 15958978571. The reversal of 15958978561 is 16587985951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15167400336 + 791578225 = 123156^2 + 28135^2 .

It is a cyclic number.

It is not a de Polignac number, because 15958978561 - 2¹⁹ = 15958454273 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 15958978493 and 15958978502.

It is not a weakly prime, because it can be changed into another prime (15958978571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7979489280 + 7979489281.

It is an arithmetic number, because the mean of its divisors is an integer number (7979489281).

Almost surely, 2^15958978561 is an apocalyptic number.

It is an amenable number.

15958978561 is a deficient number, since it is larger than the sum of its proper divisors (1).

15958978561 is an equidigital number, since it uses as much as digits as its factorization.

15958978561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216000, while the sum is 64.

The spelling of 15958978561 in words is "fifteen billion, nine hundred fifty-eight million, nine hundred seventy-eight thousand, five hundred sixty-one".