13639921 has 8 divisors (see below), whose sum is σ = 14238504. Its totient is φ = 13054080.

The previous prime is 13639919. The next prime is 13639937. The reversal of 13639921 is 12993631.

It can be written as a sum of positive squares in 4 ways, for example, as 3629025 + 10010896 = 1905^2 + 3164^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 13639921 - 2¹ = 13639919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13639961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 966 + ... + 5311.

It is an arithmetic number, because the mean of its divisors is an integer number (1779813).

Almost surely, 2^13639921 is an apocalyptic number.

It is an amenable number.

13639921 is a deficient number, since it is larger than the sum of its proper divisors (598583).

13639921 is an equidigital number, since it uses as much as digits as its factorization.

13639921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6371.

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

The square root of 13639921 is about 3693.2263672838. The cubic root of 13639921 is about 238.9299643649.

The spelling of 13639921 in words is "thirteen million, six hundred thirty-nine thousand, nine hundred twenty-one".