18218761 has 4 divisors (see below), whose sum is σ = 19875024. Its totient is φ = 16562500.

The previous prime is 18218729. The next prime is 18218771. The reversal of 18218761 is 16781281.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16781281 = 11 ⋅1525571.

It is a cyclic number.

It is not a de Polignac number, because 18218761 - 2⁵ = 18218729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18218771) 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, 828115 + ... + 828136.

It is an arithmetic number, because the mean of its divisors is an integer number (4968756).

Almost surely, 2^18218761 is an apocalyptic number.

18218761 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18218761 is a deficient number, since it is larger than the sum of its proper divisors (1656263).

18218761 is a wasteful number, since it uses less digits than its factorization.

18218761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1656262.

The product of its digits is 5376, while the sum is 34.

The square root of 18218761 is about 4268.3440582971. The cubic root of 18218761 is about 263.1315634700.

The spelling of 18218761 in words is "eighteen million, two hundred eighteen thousand, seven hundred sixty-one".