18781540 has 24 divisors (see below), whose sum is σ = 40360320. Its totient is φ = 7337568.

The previous prime is 18781537. The next prime is 18781561. The reversal of 18781540 is 4518781.

It is a junction number, because it is equal to n+sod(n) for n = 18781496 and 18781505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10060 + ... + 11779.

It is an arithmetic number, because the mean of its divisors is an integer number (1681680).

Almost surely, 2^18781540 is an apocalyptic number.

18781540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18781540 is an abundant number, since it is smaller than the sum of its proper divisors (21578780).

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

18781540 is a wasteful number, since it uses less digits than its factorization.

18781540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21891 (or 21889 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 34.

The square root of 18781540 is about 4333.7674141560. The cubic root of 18781540 is about 265.8135199662.

It can be divided in two parts, 18781 and 540, that added together give a square (19321 = 139²).

The spelling of 18781540 in words is "eighteen million, seven hundred eighty-one thousand, five hundred forty".