13891987 has 2 divisors, whose sum is σ = 13891988. Its totient is φ = 13891986.

The previous prime is 13891979. The next prime is 13891993. The reversal of 13891987 is 78919831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 13891987 - 2³ = 13891979 is a prime.

It is not a weakly prime, because it can be changed into another prime (13891187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6945993 + 6945994.

It is an arithmetic number, because the mean of its divisors is an integer number (6945994).

Almost surely, 2^13891987 is an apocalyptic number.

13891987 is a deficient number, since it is larger than the sum of its proper divisors (1).

13891987 is an equidigital number, since it uses as much as digits as its factorization.

13891987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 46.

The square root of 13891987 is about 3727.1955945456. The cubic root of 13891987 is about 240.3928000535.

It can be divided in two parts, 13891 and 987, that added together give a triangular number (14878 = T₁₇₂).

The spelling of 13891987 in words is "thirteen million, eight hundred ninety-one thousand, nine hundred eighty-seven".