18921328049 has 24 divisors (see below), whose sum is σ = 22835852640. Its totient is φ = 15573212928.

The previous prime is 18921327979. The next prime is 18921328057. The reversal of 18921328049 is 94082312981.

It is a de Polignac number, because none of the positive numbers 2^k-18921328049 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18921327994 and 18921328012.

It is not an unprimeable number, because it can be changed into a prime (18921328079) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 118727 + ... + 227900.

It is an arithmetic number, because the mean of its divisors is an integer number (951493860).

Almost surely, 2^18921328049 is an apocalyptic number.

18921328049 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

18921328049 is a deficient number, since it is larger than the sum of its proper divisors (3914524591).

18921328049 is a wasteful number, since it uses less digits than its factorization.

18921328049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 346689 (or 346676 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 47.

The spelling of 18921328049 in words is "eighteen billion, nine hundred twenty-one million, three hundred twenty-eight thousand, forty-nine".