18791840 has 48 divisors (see below), whose sum is σ = 44665992. Its totient is φ = 7471104.

The previous prime is 18791837. The next prime is 18791873. The reversal of 18791840 is 4819781.

It can be written as a sum of positive squares in 4 ways, for example, as 18696976 + 94864 = 4324^2 + 308^2 .

It is a junction number, because it is equal to n+sod(n) for n = 18791794 and 18791803.

It is an unprimeable 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 7 ways as a sum of consecutive naturals, for example, 40892 + ... + 41348.

Almost surely, 2^18791840 is an apocalyptic number.

18791840 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 18791840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22332996).

18791840 is an abundant number, since it is smaller than the sum of its proper divisors (25874152).

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

18791840 is a wasteful number, since it uses less digits than its factorization.

18791840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 729 (or 721 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 18791840 is about 4334.9555937749. The cubic root of 18791840 is about 265.8621027575.

The spelling of 18791840 in words is "eighteen million, seven hundred ninety-one thousand, eight hundred forty".