1511991 has 12 divisors (see below), whose sum is σ = 2352168. Its totient is φ = 930384.

The previous prime is 1511977. The next prime is 1511999. The reversal of 1511991 is 1991151.

It is not a de Polignac number, because 1511991 - 2⁶ = 1511927 is a prime.

It is a super-2 number, since 2×1511991² = 4572233568162, which contains 22 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

1511991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1511999) by changing a digit.

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 in 11 ways as a sum of consecutive naturals, for example, 6345 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (196014).

2^1511991 is an apocalyptic number.

1511991 is a deficient number, since it is larger than the sum of its proper divisors (840177).

1511991 is a wasteful number, since it uses less digits than its factorization.

1511991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12942 (or 12939 counting only the distinct ones).

The product of its digits is 405, while the sum is 27.

The square root of 1511991 is about 1229.6304322844. The cubic root of 1511991 is about 114.7756432360.

The spelling of 1511991 in words is "one million, five hundred eleven thousand, nine hundred ninety-one".