13531981 has 4 divisors (see below), whose sum is σ = 14120352. Its totient is φ = 12943612.

The previous prime is 13531979. The next prime is 13531993. The reversal of 13531981 is 18913531.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 13531981 - 2¹ = 13531979 is a prime.

It is a super-2 number, since 2×13531981² = 366229019568722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13531181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 294151 + ... + 294196.

It is an arithmetic number, because the mean of its divisors is an integer number (3530088).

Almost surely, 2^13531981 is an apocalyptic number.

It is an amenable number.

13531981 is a deficient number, since it is larger than the sum of its proper divisors (588371).

13531981 is an equidigital number, since it uses as much as digits as its factorization.

13531981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588370.

The product of its digits is 3240, while the sum is 31.

The square root of 13531981 is about 3678.5841026134. The cubic root of 13531981 is about 238.2980342308.

The spelling of 13531981 in words is "thirteen million, five hundred thirty-one thousand, nine hundred eighty-one".