15679991 has 4 divisors (see below), whose sum is σ = 15783984. Its totient is φ = 15576000.

The previous prime is 15679987. The next prime is 15680003. The reversal of 15679991 is 19997651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19997651 = 1117 ⋅17903.

It is a cyclic number.

It is not a de Polignac number, because 15679991 - 2² = 15679987 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 (15679901) 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, 51770 + ... + 52071.

It is an arithmetic number, because the mean of its divisors is an integer number (3945996).

Almost surely, 2^15679991 is an apocalyptic number.

15679991 is a deficient number, since it is larger than the sum of its proper divisors (103993).

15679991 is a wasteful number, since it uses less digits than its factorization.

15679991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103992.

The product of its digits is 153090, while the sum is 47.

The square root of 15679991 is about 3959.7968382229. The cubic root of 15679991 is about 250.2929419393.

The spelling of 15679991 in words is "fifteen million, six hundred seventy-nine thousand, nine hundred ninety-one".