18781992 has 24 divisors (see below), whose sum is σ = 50868090. Its totient is φ = 6260640.

The previous prime is 18781979. The next prime is 18781993. The reversal of 18781992 is 29918781.

It can be written as a sum of positive squares in only one way, i.e., 18610596 + 171396 = 4314^2 + 414^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (18781993) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 130359 + ... + 130502.

Almost surely, 2^18781992 is an apocalyptic number.

18781992 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18781992 is an abundant number, since it is smaller than the sum of its proper divisors (32086098).

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

18781992 is a wasteful number, since it uses less digits than its factorization.

18781992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260873 (or 260866 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 18781992 is about 4333.8195624645. The cubic root of 18781992 is about 265.8156523215.

The spelling of 18781992 in words is "eighteen million, seven hundred eighty-one thousand, nine hundred ninety-two".