18501791321 has 8 divisors (see below), whose sum is σ = 19944309000. Its totient is φ = 17062031232.

The previous prime is 18501791279. The next prime is 18501791333. The reversal of 18501791321 is 12319710581.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4117147225 + 14384644096 = 64165^2 + 119936^2 .

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 18501791321 - 2¹⁰ = 18501790297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18501791821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 675446 + ... + 702303.

It is an arithmetic number, because the mean of its divisors is an integer number (2493038625).

Almost surely, 2^18501791321 is an apocalyptic number.

It is an amenable number.

18501791321 is a deficient number, since it is larger than the sum of its proper divisors (1442517679).

18501791321 is a wasteful number, since it uses less digits than its factorization.

18501791321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1378795.

The product of its (nonzero) digits is 15120, while the sum is 38.

The spelling of 18501791321 in words is "eighteen billion, five hundred one million, seven hundred ninety-one thousand, three hundred twenty-one".