15999491 has 2 divisors, whose sum is σ = 15999492. Its totient is φ = 15999490.

The previous prime is 15999461. The next prime is 15999509. The reversal of 15999491 is 19499951.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (19499951) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15999491 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (15999461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7999745 + 7999746.

It is an arithmetic number, because the mean of its divisors is an integer number (7999746).

Almost surely, 2^15999491 is an apocalyptic number.

15999491 is a deficient number, since it is larger than the sum of its proper divisors (1).

15999491 is an equidigital number, since it uses as much as digits as its factorization.

15999491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 131220, while the sum is 47.

The square root of 15999491 is about 3999.9363744940. The cubic root of 15999491 is about 251.9815378681.

The spelling of 15999491 in words is "fifteen million, nine hundred ninety-nine thousand, four hundred ninety-one".