18890156339521 has 4 divisors (see below), whose sum is σ = 19400701105492. Its totient is φ = 18379611573552.

The previous prime is 18890156339519. The next prime is 18890156339569. The reversal of 18890156339521 is 12593365109881.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11853312522496 + 7036843817025 = 3442864^2 + 2652705^2 .

It is a cyclic number.

It is not a de Polignac number, because 18890156339521 - 2¹ = 18890156339519 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18890156339521.

It is not an unprimeable number, because it can be changed into a prime (18890156339501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255272382930 + ... + 255272383003.

It is an arithmetic number, because the mean of its divisors is an integer number (4850175276373).

Almost surely, 2^{18890156339521} is an apocalyptic number.

It is an amenable number.

18890156339521 is a deficient number, since it is larger than the sum of its proper divisors (510544765971).

18890156339521 is an equidigital number, since it uses as much as digits as its factorization.

18890156339521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 510544765970.

The product of its (nonzero) digits is 13996800, while the sum is 61.

The spelling of 18890156339521 in words is "eighteen trillion, eight hundred ninety billion, one hundred fifty-six million, three hundred thirty-nine thousand, five hundred twenty-one".