11631581 has 8 divisors (see below), whose sum is σ = 12958680. Its totient is φ = 10366272.

The previous prime is 11631559. The next prime is 11631589. The reversal of 11631581 is 18513611.

It can be written as a sum of positive squares in 4 ways, for example, as 3481 + 11628100 = 59^2 + 3410^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11631581 is a prime.

It is a super-2 number, since 2×11631581² = 270587353119122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 11631581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11631589) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15050 + ... + 15803.

It is an arithmetic number, because the mean of its divisors is an integer number (1619835).

Almost surely, 2^11631581 is an apocalyptic number.

It is an amenable number.

11631581 is a deficient number, since it is larger than the sum of its proper divisors (1327099).

11631581 is a wasteful number, since it uses less digits than its factorization.

11631581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30895.

The product of its digits is 720, while the sum is 26.

The square root of 11631581 is about 3410.5103723636. The cubic root of 11631581 is about 226.5754840375.

It can be divided in two parts, 1163 and 1581, that added together give a cube (2744 = 14³).

The spelling of 11631581 in words is "eleven million, six hundred thirty-one thousand, five hundred eighty-one".