18621665 has 4 divisors (see below), whose sum is σ = 22346004. Its totient is φ = 14897328.

The previous prime is 18621661. The next prime is 18621671. The reversal of 18621665 is 56612681.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2007889 + 16613776 = 1417^2 + 4076^2 .

It is a cyclic number.

It is not a de Polignac number, because 18621665 - 2² = 18621661 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18621661) 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, 1862162 + ... + 1862171.

It is an arithmetic number, because the mean of its divisors is an integer number (5586501).

Almost surely, 2^18621665 is an apocalyptic number.

It is an amenable number.

18621665 is a deficient number, since it is larger than the sum of its proper divisors (3724339).

18621665 is an equidigital number, since it uses as much as digits as its factorization.

18621665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3724338.

The product of its digits is 17280, while the sum is 35.

The square root of 18621665 is about 4315.2827253843. The cubic root of 18621665 is about 265.0571373177.

The spelling of 18621665 in words is "eighteen million, six hundred twenty-one thousand, six hundred sixty-five".