18781920 has 72 divisors (see below), whose sum is σ = 64098216. Its totient is φ = 5008128.

The previous prime is 18781913. The next prime is 18781921. The reversal of 18781920 is 2918781.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18781921) 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, 5082 + ... + 7961.

It is an arithmetic number, because the mean of its divisors is an integer number (890253).

Almost surely, 2^18781920 is an apocalyptic number.

18781920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18781920 is an abundant number, since it is smaller than the sum of its proper divisors (45316296).

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

18781920 is a wasteful number, since it uses less digits than its factorization.

18781920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13064 (or 13053 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 18781920 is about 4333.8112556963. The cubic root of 18781920 is about 265.8153126566.

It can be divided in two parts, 18781 and 920, that added together give a triangular number (19701 = T₁₉₈).

The spelling of 18781920 in words is "eighteen million, seven hundred eighty-one thousand, nine hundred twenty".