18121856 has 32 divisors (see below), whose sum is σ = 37274880. Its totient is φ = 8766720.

The previous prime is 18121843. The next prime is 18121867. The reversal of 18121856 is 65812181.

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is an alternating number because its digits alternate between odd and even.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1685 + ... + 6251.

It is an arithmetic number, because the mean of its divisors is an integer number (1164840).

Almost surely, 2^18121856 is an apocalyptic number.

18121856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18121856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18637440).

18121856 is an abundant number, since it is smaller than the sum of its proper divisors (19153024).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18121856 is an equidigital number, since it uses as much as digits as its factorization.

18121856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4612 (or 4600 counting only the distinct ones).

The product of its digits is 3840, while the sum is 32.

The square root of 18121856 is about 4256.9773313937. The cubic root of 18121856 is about 262.6642044427.

The spelling of 18121856 in words is "eighteen million, one hundred twenty-one thousand, eight hundred fifty-six".