18091920 has 240 divisors, whose sum is σ = 71245440. Its totient is φ = 3717120.

The previous prime is 18091919. The next prime is 18091939. The reversal of 18091920 is 2919081.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 203236 + ... + 203324.

It is an arithmetic number, because the mean of its divisors is an integer number (296856).

Almost surely, 2^18091920 is an apocalyptic number.

18091920 is a gapful number since it is divisible by the number (10) 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 18091920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35622720).

18091920 is an abundant number, since it is smaller than the sum of its proper divisors (53153520).

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

18091920 is a wasteful number, since it uses less digits than its factorization.

18091920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 18091920 is about 4253.4597682357. The cubic root of 18091920 is about 262.5194906163.

The spelling of 18091920 in words is "eighteen million, ninety-one thousand, nine hundred twenty".