15959377816561 has 9 divisors (see below), whose sum is σ = 16020005626443. Its totient is φ = 15898978636200.

The previous prime is 15959377816559. The next prime is 15959377816699. The reversal of 15959377816561 is 16561877395951.

The square root of 15959377816561 is 3994919.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1050049028961 + 14909328787600 = 1024719^2 + 3861260^2 .

It is not a de Polignac number, because 15959377816561 - 2¹ = 15959377816559 is a prime.

It is a Duffinian number.

Its product of digits (428652000) is a multiple of the sum of its prime divisors (15120).

It is not an unprimeable number, because it can be changed into a prime (15959377817561) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1074625786 + ... + 1074640636.

Almost surely, 2^{15959377816561} is an apocalyptic number.

15959377816561 is the 3994919-th square number.

15959377816561 is the 1997460-th centered octagonal number.

It is an amenable number.

15959377816561 is a deficient number, since it is larger than the sum of its proper divisors (60627809882).

15959377816561 is an frugal number, since it uses more digits than its factorization.

15959377816561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30240 (or 15120 counting only the distinct ones).

The product of its digits is 428652000, while the sum is 73.

The spelling of 15959377816561 in words is "fifteen trillion, nine hundred fifty-nine billion, three hundred seventy-seven million, eight hundred sixteen thousand, five hundred sixty-one".