13999981 has 2 divisors, whose sum is σ = 13999982. Its totient is φ = 13999980.

The previous prime is 13999969. The next prime is 14000029. The reversal of 13999981 is 18999931.

13999981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13995081 + 4900 = 3741^2 + 70^2 .

It is a cyclic number.

It is not a de Polignac number, because 13999981 - 2²¹ = 11902829 is a prime.

It is a super-2 number, since 2×13999981² = 391998936000722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13999961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6999990 + 6999991.

It is an arithmetic number, because the mean of its divisors is an integer number (6999991).

Almost surely, 2^13999981 is an apocalyptic number.

It is an amenable number.

13999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

13999981 is an equidigital number, since it uses as much as digits as its factorization.

13999981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 157464, while the sum is 49.

The square root of 13999981 is about 3741.6548477913. The cubic root of 13999981 is about 241.0141173872.

The spelling of 13999981 in words is "thirteen million, nine hundred ninety-nine thousand, nine hundred eighty-one".