15668639 has 4 divisors (see below), whose sum is σ = 17907024. Its totient is φ = 13430256.

The previous prime is 15668633. The next prime is 15668651. The reversal of 15668639 is 93686651.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 15668639 - 2¹⁶ = 15603103 is a prime.

It is a super-2 number, since 2×15668639² = 491012496224642, which contains 22 as substring.

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 15668639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15668633) 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, 1119182 + ... + 1119195.

It is an arithmetic number, because the mean of its divisors is an integer number (4476756).

Almost surely, 2^15668639 is an apocalyptic number.

15668639 is a deficient number, since it is larger than the sum of its proper divisors (2238385).

15668639 is an equidigital number, since it uses as much as digits as its factorization.

15668639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2238384.

The product of its digits is 233280, while the sum is 44.

The square root of 15668639 is about 3958.3631718174. The cubic root of 15668639 is about 250.2325249948.

The spelling of 15668639 in words is "fifteen million, six hundred sixty-eight thousand, six hundred thirty-nine".