1311815961 has 9 divisors (see below), whose sum is σ = 1895002239. Its totient is φ = 874471536.

The previous prime is 1311815941. The next prime is 1311815987. The reversal of 1311815961 is 1695181131.

The square root of 1311815961 is 36219.

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., 26163225 + 1285652736 = 5115^2 + 35856^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1311815961 - 2¹¹ = 1311813913 is a prime.

It is a super-2 number, since 2×1311815961² = 3441722231068707042, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1311815941) 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, 102621 + ... + 114693.

Almost surely, 2^1311815961 is an apocalyptic number.

1311815961 is the 36219-th square number.

1311815961 is the 18110-th centered octagonal number.

It is an amenable number.

1311815961 is a deficient number, since it is larger than the sum of its proper divisors (583186278).

1311815961 is an frugal number, since it uses more digits than its factorization.

1311815961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24152 (or 12076 counting only the distinct ones).

The product of its digits is 6480, while the sum is 36.

The cubic root of 1311815961 is about 1094.6895448145.

Multiplying 1311815961 by its sum of digits (36), we get a square (47225374596 = 217314²).

The spelling of 1311815961 in words is "one billion, three hundred eleven million, eight hundred fifteen thousand, nine hundred sixty-one".