18431920 has 80 divisors (see below), whose sum is σ = 47496960. Its totient is φ = 6607872.

The previous prime is 18431879. The next prime is 18431923. The reversal of 18431920 is 2913481.

18431920 = T₁ + T₂ + ... + T₄₇₉.

It is a happy number.

18431920 is a nontrivial binomial coefficient, being equal to C(481, 3).

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (18431923) by changing a digit.

It is the 479-th tetrahedral number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38241 + ... + 38719.

It is an arithmetic number, because the mean of its divisors is an integer number (593712).

Almost surely, 2^18431920 is an apocalyptic number.

18431920 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 18431920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23748480).

18431920 is an abundant number, since it is smaller than the sum of its proper divisors (29065040).

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

18431920 is a wasteful number, since it uses less digits than its factorization.

18431920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542 (or 536 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 18431920 is about 4293.2411998396. The cubic root of 18431920 is about 264.1537977435.

The spelling of 18431920 in words is "eighteen million, four hundred thirty-one thousand, nine hundred twenty".