15994407961 has 45 divisors (see below), whose sum is σ = 19544204381. Its totient is φ = 13088023872.

The previous prime is 15994407953. The next prime is 15994407971. The reversal of 15994407961 is 16970449951.

The square root of 15994407961 is 126469.

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

It can be written as a sum of positive squares in 4 ways, for example, as 1464516361 + 14529891600 = 38269^2 + 120540^2 .

It is not a de Polignac number, because 15994407961 - 2³ = 15994407953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15994407941) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 179712405 + ... + 179712493.

Almost surely, 2^15994407961 is an apocalyptic number.

15994407961 is the 126469-th square number.

15994407961 is the 63235-th centered octagonal number.

It is an amenable number.

15994407961 is a deficient number, since it is larger than the sum of its proper divisors (3549796420).

15994407961 is an frugal number, since it uses more digits than its factorization.

15994407961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264 (or 125 counting only the distinct ones).

The product of its (nonzero) digits is 2449440, while the sum is 55.

The spelling of 15994407961 in words is "fifteen billion, nine hundred ninety-four million, four hundred seven thousand, nine hundred sixty-one".