13991557 has 2 divisors, whose sum is σ = 13991558. Its totient is φ = 13991556.

The previous prime is 13991533. The next prime is 13991563. The reversal of 13991557 is 75519931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10719076 + 3272481 = 3274^2 + 1809^2 .

It is a cyclic number.

It is not a de Polignac number, because 13991557 - 2¹⁹ = 13467269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13991507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6995778 + 6995779.

It is an arithmetic number, because the mean of its divisors is an integer number (6995779).

Almost surely, 2^13991557 is an apocalyptic number.

It is an amenable number.

13991557 is a deficient number, since it is larger than the sum of its proper divisors (1).

13991557 is an equidigital number, since it uses as much as digits as its factorization.

13991557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42525, while the sum is 40.

The square root of 13991557 is about 3740.5289732871. The cubic root of 13991557 is about 240.9657670768.

The spelling of 13991557 in words is "thirteen million, nine hundred ninety-one thousand, five hundred fifty-seven".