18057991901 has 4 divisors (see below), whose sum is σ = 18058266204. Its totient is φ = 18057717600.

The previous prime is 18057991829. The next prime is 18057991961. The reversal of 18057991901 is 10919975081.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 10919975081 = 271 ⋅40295111.

It can be written as a sum of positive squares in 2 ways, for example, as 11610062500 + 6447929401 = 107750^2 + 80299^2 .

It is a cyclic number.

It is not a de Polignac number, because 18057991901 - 2¹⁸ = 18057729757 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18057991901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18057991961) 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, 27431 + ... + 192011.

It is an arithmetic number, because the mean of its divisors is an integer number (4514566551).

It is a Poulet number, since it divides 2^18057991900-1.

Almost surely, 2^18057991901 is an apocalyptic number.

18057991901 is the 109721-st pentagonal number.

It is an amenable number.

18057991901 is a deficient number, since it is larger than the sum of its proper divisors (274303).

18057991901 is a wasteful number, since it uses less digits than its factorization.

18057991901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274302.

The product of its (nonzero) digits is 204120, while the sum is 50.

The spelling of 18057991901 in words is "eighteen billion, fifty-seven million, nine hundred ninety-one thousand, nine hundred one".