18216761 has 4 divisors (see below), whose sum is σ = 18237300. Its totient is φ = 18196224.

The previous prime is 18216749. The next prime is 18216767. The reversal of 18216761 is 16761281.

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 9985600 + 8231161 = 3160^2 + 2869^2 .

It is a cyclic number.

It is not a de Polignac number, because 18216761 - 2¹⁸ = 17954617 is a prime.

It is a super-2 number, since 2×18216761² = 663700762662242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18216767) 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, 8876 + ... + 10733.

It is an arithmetic number, because the mean of its divisors is an integer number (4559325).

Almost surely, 2^18216761 is an apocalyptic number.

It is an amenable number.

18216761 is a deficient number, since it is larger than the sum of its proper divisors (20539).

18216761 is an equidigital number, since it uses as much as digits as its factorization.

18216761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20538.

The product of its digits is 4032, while the sum is 32.

The square root of 18216761 is about 4268.1097689727. The cubic root of 18216761 is about 263.1219345242.

The spelling of 18216761 in words is "eighteen million, two hundred sixteen thousand, seven hundred sixty-one".