13978661 has 4 divisors (see below), whose sum is σ = 14714400. Its totient is φ = 13242924.

The previous prime is 13978649. The next prime is 13978669. The reversal of 13978661 is 16687931.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 13978661 - 2¹⁸ = 13716517 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13978669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 367841 + ... + 367878.

It is an arithmetic number, because the mean of its divisors is an integer number (3678600).

Almost surely, 2^13978661 is an apocalyptic number.

It is an amenable number.

13978661 is a deficient number, since it is larger than the sum of its proper divisors (735739).

13978661 is an equidigital number, since it uses as much as digits as its factorization.

13978661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 735738.

The product of its digits is 54432, while the sum is 41.

The square root of 13978661 is about 3738.8047555335. The cubic root of 13978661 is about 240.8917117079.

The spelling of 13978661 in words is "thirteen million, nine hundred seventy-eight thousand, six hundred sixty-one".