13311981 has 6 divisors (see below), whose sum is σ = 19228430. Its totient is φ = 8874648.

The previous prime is 13311973. The next prime is 13312001. The reversal of 13311981 is 18911331.

It is a happy number.

13311981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 11088900 + 2223081 = 3330^2 + 1491^2 .

It is not a de Polignac number, because 13311981 - 2³ = 13311973 is a prime.

It is a super-2 number, since 2×13311981² = 354417676288722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13311911) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 739546 + ... + 739563.

Almost surely, 2^13311981 is an apocalyptic number.

It is an amenable number.

13311981 is a deficient number, since it is larger than the sum of its proper divisors (5916449).

13311981 is a wasteful number, since it uses less digits than its factorization.

13311981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1479115 (or 1479112 counting only the distinct ones).

The product of its digits is 648, while the sum is 27.

The square root of 13311981 is about 3648.5587565503. The cubic root of 13311981 is about 236.9995727173. Note that the first 3 decimals are identical.

The spelling of 13311981 in words is "thirteen million, three hundred eleven thousand, nine hundred eighty-one".