18661989792 has 48 divisors (see below), whose sum is σ = 49001500800. Its totient is φ = 6218913792.

The previous prime is 18661989779. The next prime is 18661989793. The reversal of 18661989792 is 29798916681.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (18661989793) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 341584 + ... + 392432.

It is an arithmetic number, because the mean of its divisors is an integer number (1020864600).

Almost surely, 2^18661989792 is an apocalyptic number.

18661989792 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18661989792 is an abundant number, since it is smaller than the sum of its proper divisors (30339511008).

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

18661989792 is a wasteful number, since it uses less digits than its factorization.

18661989792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54685 (or 54677 counting only the distinct ones).

The product of its digits is 23514624, while the sum is 66.

The spelling of 18661989792 in words is "eighteen billion, six hundred sixty-one million, nine hundred eighty-nine thousand, seven hundred ninety-two".