18781020 has 72 divisors (see below), whose sum is σ = 57578976. Its totient is φ = 4954752.

The previous prime is 18781013. The next prime is 18781033. The reversal of 18781020 is 2018781.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 18034 + ... + 19046.

It is an arithmetic number, because the mean of its divisors is an integer number (799708).

Almost surely, 2^18781020 is an apocalyptic number.

18781020 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 18781020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28789488).

18781020 is an abundant number, since it is smaller than the sum of its proper divisors (38797956).

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

18781020 is a wasteful number, since it uses less digits than its factorization.

18781020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1131 (or 1126 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 18781020 is about 4333.7074197504. The cubic root of 18781020 is about 265.8110667718.

The spelling of 18781020 in words is "eighteen million, seven hundred eighty-one thousand, twenty".