13987989 has 6 divisors (see below), whose sum is σ = 20204886. Its totient is φ = 9325320.

The previous prime is 13987969. The next prime is 13987997. The reversal of 13987989 is 98978931.

13987989 is digitally balanced in base 2, 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., 10595025 + 3392964 = 3255^2 + 1842^2 .

It is not a de Polignac number, because 13987989 - 2⁸ = 13987733 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13987949) 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, 777102 + ... + 777119.

It is an arithmetic number, because the mean of its divisors is an integer number (3367481).

Almost surely, 2^13987989 is an apocalyptic number.

It is an amenable number.

13987989 is a deficient number, since it is larger than the sum of its proper divisors (6216897).

13987989 is a wasteful number, since it uses less digits than its factorization.

13987989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1554227 (or 1554224 counting only the distinct ones).

The product of its digits is 979776, while the sum is 54.

The square root of 13987989 is about 3740.0520049860. The cubic root of 13987989 is about 240.9452823671.

The spelling of 13987989 in words is "thirteen million, nine hundred eighty-seven thousand, nine hundred eighty-nine".