13991388 has 12 divisors (see below), whose sum is σ = 32646600. Its totient is φ = 4663792.

The previous prime is 13991381. The next prime is 13991389. The reversal of 13991388 is 88319931.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13991381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 582963 + ... + 582986.

It is an arithmetic number, because the mean of its divisors is an integer number (2720550).

Almost surely, 2^13991388 is an apocalyptic number.

It is an amenable number.

13991388 is an abundant number, since it is smaller than the sum of its proper divisors (18655212).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

13991388 is a wasteful number, since it uses less digits than its factorization.

13991388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1165956 (or 1165954 counting only the distinct ones).

The product of its digits is 46656, while the sum is 42.

The square root of 13991388 is about 3740.5063828311. The cubic root of 13991388 is about 240.9647968874.

The spelling of 13991388 in words is "thirteen million, nine hundred ninety-one thousand, three hundred eighty-eight".