13115531 has 16 divisors (see below), whose sum is σ = 15791328. Its totient is φ = 10732800.

The previous prime is 13115527. The next prime is 13115533. The reversal of 13115531 is 13551131.

It is not a de Polignac number, because 13115531 - 2² = 13115527 is a prime.

It is a super-2 number, since 2×13115531² = 344034306823922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13115533) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4745 + ... + 6981.

It is an arithmetic number, because the mean of its divisors is an integer number (986958).

Almost surely, 2^13115531 is an apocalyptic number.

13115531 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

13115531 is a deficient number, since it is larger than the sum of its proper divisors (2675797).

13115531 is a wasteful number, since it uses less digits than its factorization.

13115531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2302.

The product of its digits is 225, while the sum is 20.

The square root of 13115531 is about 3621.5371046008. The cubic root of 13115531 is about 235.8279592172.

Adding to 13115531 its reverse (13551131), we get a palindrome (26666662).

Subtracting 13115531 from its reverse (13551131), we obtain a square (435600 = 660²).

The spelling of 13115531 in words is "thirteen million, one hundred fifteen thousand, five hundred thirty-one".