15991057 has 4 divisors (see below), whose sum is σ = 16067056. Its totient is φ = 15915060.

The previous prime is 15991037. The next prime is 15991097. The reversal of 15991057 is 75019951.

It is a happy number.

15991057 is an esthetic number in base 12, because in such base its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75019951 = 23 ⋅3261737.

It is a cyclic number.

It is not a de Polignac number, because 15991057 - 2¹⁹ = 15466769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15991007) 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, 37683 + ... + 38104.

It is an arithmetic number, because the mean of its divisors is an integer number (4016764).

Almost surely, 2^15991057 is an apocalyptic number.

It is an amenable number.

15991057 is a deficient number, since it is larger than the sum of its proper divisors (75999).

15991057 is an equidigital number, since it uses as much as digits as its factorization.

15991057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75998.

The product of its (nonzero) digits is 14175, while the sum is 37.

The square root of 15991057 is about 3998.8819687508. The cubic root of 15991057 is about 251.9372534212.

The spelling of 15991057 in words is "fifteen million, nine hundred ninety-one thousand, fifty-seven".