18121791 has 16 divisors (see below), whose sum is σ = 25153920. Its totient is φ = 11595360.

The previous prime is 18121787. The next prime is 18121799. The reversal of 18121791 is 19712181.

It is not a de Polignac number, because 18121791 - 2² = 18121787 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18121799) 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 15 ways as a sum of consecutive naturals, for example, 6421 + ... + 8801.

It is an arithmetic number, because the mean of its divisors is an integer number (1572120).

Almost surely, 2^18121791 is an apocalyptic number.

18121791 is a deficient number, since it is larger than the sum of its proper divisors (7032129).

18121791 is a wasteful number, since it uses less digits than its factorization.

18121791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2486.

The product of its digits is 1008, while the sum is 30.

The square root of 18121791 is about 4256.9696968618. The cubic root of 18121791 is about 262.6638903984.

The spelling of 18121791 in words is "eighteen million, one hundred twenty-one thousand, seven hundred ninety-one".