18936640 has 84 divisors (see below), whose sum is σ = 48568356. Its totient is φ = 7008256.

The previous prime is 18936611. The next prime is 18936647. The reversal of 18936640 is 4663981.

It can be written as a sum of positive squares in 2 ways, for example, as 10916416 + 8020224 = 3304^2 + 2832^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18936640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18936647) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 320931 + ... + 320989.

Almost surely, 2^18936640 is an apocalyptic number.

18936640 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 18936640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24284178).

18936640 is an abundant number, since it is smaller than the sum of its proper divisors (29631716).

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

18936640 is an equidigital number, since it uses as much as digits as its factorization.

18936640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152 (or 83 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 18936640 is about 4351.6249838422. The cubic root of 18936640 is about 266.5432206406.

The spelling of 18936640 in words is "eighteen million, nine hundred thirty-six thousand, six hundred forty".