15999951 has 16 divisors (see below), whose sum is σ = 23470848. Its totient is φ = 9694520.

The previous prime is 15999931. The next prime is 15999953.

It is a happy number.

15999951 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 15999951 - 2⁹ = 15999439 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 15999951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15999953) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1990 + ... + 5996.

It is an arithmetic number, because the mean of its divisors is an integer number (1466928).

Almost surely, 2^15999951 is an apocalyptic number.

15999951 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

15999951 is a deficient number, since it is larger than the sum of its proper divisors (7470897).

15999951 is an equidigital number, since it uses as much as digits as its factorization.

15999951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4043 (or 4021 counting only the distinct ones).

The product of its digits is 164025, while the sum is 48.

The square root of 15999951 is about 3999.9938749953. The cubic root of 15999951 is about 251.9839527448.

The spelling of 15999951 in words is "fifteen million, nine hundred ninety-nine thousand, nine hundred fifty-one".