18187961 has 4 divisors (see below), whose sum is σ = 19841424. Its totient is φ = 16534500.

The previous prime is 18187937. The next prime is 18187973. The reversal of 18187961 is 16978181.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18187961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18187931) 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, 826715 + ... + 826736.

It is an arithmetic number, because the mean of its divisors is an integer number (4960356).

Almost surely, 2^18187961 is an apocalyptic number.

18187961 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18187961 is a deficient number, since it is larger than the sum of its proper divisors (1653463).

18187961 is a wasteful number, since it uses less digits than its factorization.

18187961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1653462.

The product of its digits is 24192, while the sum is 41.

The square root of 18187961 is about 4264.7345755627. The cubic root of 18187961 is about 262.9831994935.

It can be divided in two parts, 1818 and 7961, that added together give a palindrome (9779).

The spelling of 18187961 in words is "eighteen million, one hundred eighty-seven thousand, nine hundred sixty-one".