18690451921 has 8 divisors (see below), whose sum is σ = 19388678400. Its totient is φ = 18003766560.

The previous prime is 18690451919. The next prime is 18690451979. The reversal of 18690451921 is 12915409681.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 18690451921 - 2¹ = 18690451919 is a prime.

It is a super-2 number, since 2×18690451921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18690451421) 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, 2881981 + ... + 2888458.

It is an arithmetic number, because the mean of its divisors is an integer number (2423584800).

Almost surely, 2^18690451921 is an apocalyptic number.

It is an amenable number.

18690451921 is a deficient number, since it is larger than the sum of its proper divisors (698226479).

18690451921 is an equidigital number, since it uses as much as digits as its factorization.

18690451921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5770559.

The product of its (nonzero) digits is 155520, while the sum is 46.

The spelling of 18690451921 in words is "eighteen billion, six hundred ninety million, four hundred fifty-one thousand, nine hundred twenty-one".