15996665 has 4 divisors (see below), whose sum is σ = 19196004. Its totient is φ = 12797328.

The previous prime is 15996649. The next prime is 15996667. The reversal of 15996665 is 56669951.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2768896 + 13227769 = 1664^2 + 3637^2 .

It is a cyclic number.

It is not a de Polignac number, because 15996665 - 2⁴ = 15996649 is a prime.

It is a super-2 number, since 2×15996665² = 511786582244450, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (15996667) 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, 1599662 + ... + 1599671.

It is an arithmetic number, because the mean of its divisors is an integer number (4799001).

Almost surely, 2^15996665 is an apocalyptic number.

It is an amenable number.

15996665 is a deficient number, since it is larger than the sum of its proper divisors (3199339).

15996665 is an equidigital number, since it uses as much as digits as its factorization.

15996665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3199338.

The product of its digits is 437400, while the sum is 47.

The square root of 15996665 is about 3999.5831032746. The cubic root of 15996665 is about 251.9667011095.

It can be divided in two parts, 15996 and 665, that added together give a palindrome (16661).

The spelling of 15996665 in words is "fifteen million, nine hundred ninety-six thousand, six hundred sixty-five".