13921639 has 4 divisors (see below), whose sum is σ = 13929280. Its totient is φ = 13914000.

The previous prime is 13921571. The next prime is 13921643. The reversal of 13921639 is 93612931.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 13921639 - 2²¹ = 11824487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13921679) 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, 682 + ... + 5320.

It is an arithmetic number, because the mean of its divisors is an integer number (3482320).

Almost surely, 2^13921639 is an apocalyptic number.

13921639 is a deficient number, since it is larger than the sum of its proper divisors (7641).

13921639 is an equidigital number, since it uses as much as digits as its factorization.

13921639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7640.

The product of its digits is 8748, while the sum is 34.

The square root of 13921639 is about 3731.1712638259. The cubic root of 13921639 is about 240.5637154098.

The spelling of 13921639 in words is "thirteen million, nine hundred twenty-one thousand, six hundred thirty-nine".