13639861 has 4 divisors (see below), whose sum is σ = 13647424. Its totient is φ = 13632300.

The previous prime is 13639859. The next prime is 13639867. The reversal of 13639861 is 16893631.

13639861 = T₃₀₁₄ + T₃₀₁₅ + T₃₀₁₆.

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, 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 13639861 - 2¹ = 13639859 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 13639861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13639867) 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, 676 + ... + 5266.

It is an arithmetic number, because the mean of its divisors is an integer number (3411856).

Almost surely, 2^13639861 is an apocalyptic number.

13639861 is the 3016-th centered triangular number.

It is an amenable number.

13639861 is a deficient number, since it is larger than the sum of its proper divisors (7563).

13639861 is an equidigital number, since it uses as much as digits as its factorization.

13639861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7562.

The product of its digits is 23328, while the sum is 37.

The square root of 13639861 is about 3693.2182442959. The cubic root of 13639861 is about 238.9296140252.

The spelling of 13639861 in words is "thirteen million, six hundred thirty-nine thousand, eight hundred sixty-one".