15999994 has 8 divisors (see below), whose sum is σ = 24328980. Its totient is φ = 7890336.

The previous prime is 15999989. The next prime is 16000057. The reversal of 15999994 is 49999951.

It can be written as a sum of positive squares in 2 ways, for example, as 14707225 + 1292769 = 3835^2 + 1137^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54649 + ... + 54940.

Almost surely, 2^15999994 is an apocalyptic number.

15999994 is a deficient number, since it is larger than the sum of its proper divisors (8328986).

15999994 is a wasteful number, since it uses less digits than its factorization.

15999994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109664.

The product of its digits is 1180980, while the sum is 55.

The square root of 15999994 is about 3999.9992499999. Note that the first 3 decimals coincide. The cubic root of 15999994 is about 251.9841784809.

It can be divided in two parts, 1 and 5999994, that added together give a palindrome (5999995).

The spelling of 15999994 in words is "fifteen million, nine hundred ninety-nine thousand, nine hundred ninety-four".