18660786991 has 8 divisors (see below), whose sum is σ = 23265396864. Its totient is φ = 14540872920.

The previous prime is 18660786943. The next prime is 18660787111. The reversal of 18660786991 is 19968706681.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18660786991 - 2⁹ = 18660786479 is a prime.

It is a super-2 number, since 2×18660786991² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18660784991) 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, 121173865 + ... + 121174018.

It is an arithmetic number, because the mean of its divisors is an integer number (2908174608).

Almost surely, 2^18660786991 is an apocalyptic number.

18660786991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18660786991 is a deficient number, since it is larger than the sum of its proper divisors (4604609873).

18660786991 is a wasteful number, since it uses less digits than its factorization.

18660786991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242347901.

The product of its (nonzero) digits is 7838208, while the sum is 61.

The spelling of 18660786991 in words is "eighteen billion, six hundred sixty million, seven hundred eighty-six thousand, nine hundred ninety-one".