18220857 has 4 divisors (see below), whose sum is σ = 24294480. Its totient is φ = 12147236.

The previous prime is 18220849. The next prime is 18220861. The reversal of 18220857 is 75802281.

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: 75802281 = 3 ⋅25267427.

It is a cyclic number.

It is not a de Polignac number, because 18220857 - 2³ = 18220849 is a prime.

It is a super-3 number, since 3×18220857³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (18220847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3036807 + ... + 3036812.

It is an arithmetic number, because the mean of its divisors is an integer number (6073620).

Almost surely, 2^18220857 is an apocalyptic number.

It is an amenable number.

18220857 is a deficient number, since it is larger than the sum of its proper divisors (6073623).

18220857 is an equidigital number, since it uses as much as digits as its factorization.

18220857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6073622.

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 18220857 is about 4268.5895797090. The cubic root of 18220857 is about 263.1416538489.

The spelling of 18220857 in words is "eighteen million, two hundred twenty thousand, eight hundred fifty-seven".