13539981 has 16 divisors (see below), whose sum is σ = 22219904. Its totient is φ = 7141824.

The previous prime is 13539979. The next prime is 13539983. The reversal of 13539981 is 18993531.

13539981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (13539979) and next prime (13539983).

It is not a de Polignac number, because 13539981 - 2¹ = 13539979 is a prime.

It is a super-2 number, since 2×13539981² = 366662170960722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13539983) 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 15 ways as a sum of consecutive naturals, for example, 24526 + ... + 25071.

It is an arithmetic number, because the mean of its divisors is an integer number (1388744).

Almost surely, 2^13539981 is an apocalyptic number.

It is an amenable number.

13539981 is a deficient number, since it is larger than the sum of its proper divisors (8679923).

13539981 is a wasteful number, since it uses less digits than its factorization.

13539981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49620.

The product of its digits is 29160, while the sum is 39.

The square root of 13539981 is about 3679.6713168434. The cubic root of 13539981 is about 238.3449849499.

The spelling of 13539981 in words is "thirteen million, five hundred thirty-nine thousand, nine hundred eighty-one".