13978911 has 4 divisors (see below), whose sum is σ = 18638552. Its totient is φ = 9319272.

The previous prime is 13978901. The next prime is 13978931. The reversal of 13978911 is 11987931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11987931 = 3 ⋅3995977.

It is not a de Polignac number, because 13978911 - 2¹⁵ = 13946143 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 13978911.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13978901) 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, 2329816 + ... + 2329821.

It is an arithmetic number, because the mean of its divisors is an integer number (4659638).

Almost surely, 2^13978911 is an apocalyptic number.

13978911 is a deficient number, since it is larger than the sum of its proper divisors (4659641).

13978911 is an equidigital number, since it uses as much as digits as its factorization.

13978911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4659640.

The product of its digits is 13608, while the sum is 39.

The square root of 13978911 is about 3738.8381885286. The cubic root of 13978911 is about 240.8931477674.

The spelling of 13978911 in words is "thirteen million, nine hundred seventy-eight thousand, nine hundred eleven".