15999668 has 6 divisors (see below), whose sum is σ = 27999426. Its totient is φ = 7999832.

The previous prime is 15999649. The next prime is 15999701. The reversal of 15999668 is 86699951.

It can be written as a sum of positive squares in only one way, i.e., 11035684 + 4963984 = 3322^2 + 2228^2 .

It is a super-2 number, since 2×15999668² = 511978752220448, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1999955 + ... + 1999962.

It is an arithmetic number, because the mean of its divisors is an integer number (4666571).

Almost surely, 2^15999668 is an apocalyptic number.

It is an amenable number.

15999668 is a deficient number, since it is larger than the sum of its proper divisors (11999758).

15999668 is a wasteful number, since it uses less digits than its factorization.

15999668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3999921 (or 3999919 counting only the distinct ones).

The product of its digits is 1049760, while the sum is 53.

The square root of 15999668 is about 3999.9584997847. The cubic root of 15999668 is about 251.9824670761.

The spelling of 15999668 in words is "fifteen million, nine hundred ninety-nine thousand, six hundred sixty-eight".