13215531 has 8 divisors (see below), whose sum is σ = 20137984. Its totient is φ = 7551720.

The previous prime is 13215479. The next prime is 13215533. The reversal of 13215531 is 13551231.

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

It is not a de Polignac number, because 13215531 - 2¹⁰ = 13214507 is a prime.

It is a super-2 number, since 2×13215531² = 349300519223922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 629311 = 13215531 / (1 + 3 + 2 + 1 + 5 + 5 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13215498 and 13215507.

It is not an unprimeable number, because it can be changed into a prime (13215533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 314635 + ... + 314676.

It is an arithmetic number, because the mean of its divisors is an integer number (2517248).

Almost surely, 2^13215531 is an apocalyptic number.

13215531 is a deficient number, since it is larger than the sum of its proper divisors (6922453).

13215531 is an equidigital number, since it uses as much as digits as its factorization.

13215531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 629321.

The product of its digits is 450, while the sum is 21.

The square root of 13215531 is about 3635.3171801096. The cubic root of 13215531 is about 236.4258029101.

Adding to 13215531 its reverse (13551231), we get a palindrome (26766762).

The spelling of 13215531 in words is "thirteen million, two hundred fifteen thousand, five hundred thirty-one".