18997261 has 4 divisors (see below), whose sum is σ = 19009852. Its totient is φ = 18984672.

The previous prime is 18997249. The next prime is 18997273. The reversal of 18997261 is 16279981.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (18997249) and next prime (18997273).

It can be written as a sum of positive squares in 2 ways, for example, as 1932100 + 17065161 = 1390^2 + 4131^2 .

It is a cyclic number.

It is not a de Polignac number, because 18997261 - 2⁵ = 18997229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18997201) 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, 3666 + ... + 7171.

It is an arithmetic number, because the mean of its divisors is an integer number (4752463).

Almost surely, 2^18997261 is an apocalyptic number.

It is an amenable number.

18997261 is a deficient number, since it is larger than the sum of its proper divisors (12591).

18997261 is a wasteful number, since it uses less digits than its factorization.

18997261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12590.

The product of its digits is 54432, while the sum is 43.

The square root of 18997261 is about 4358.5847473693. The cubic root of 18997261 is about 266.8273418839.

The spelling of 18997261 in words is "eighteen million, nine hundred ninety-seven thousand, two hundred sixty-one".