21555355015321 has 8 divisors (see below), whose sum is σ = 21908841885000. Its totient is φ = 21201872029440.

The previous prime is 21555355015319. The next prime is 21555355015331. The reversal of 21555355015321 is 12351055355512.

It can be written as a sum of positive squares in 4 ways, for example, as 625782252096 + 20929572763225 = 791064^2 + 4574885^2 .

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 21555355015321 - 2¹ = 21555355015319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21555355015331) 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, 11528895 + ... + 13267483.

It is an arithmetic number, because the mean of its divisors is an integer number (2738605235625).

Almost surely, 2^{21555355015321} is an apocalyptic number.

It is an amenable number.

21555355015321 is a deficient number, since it is larger than the sum of its proper divisors (353486869679).

21555355015321 is a wasteful number, since it uses less digits than its factorization.

21555355015321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1941899.

The product of its (nonzero) digits is 562500, while the sum is 43.

The spelling of 21555355015321 in words is "twenty-one trillion, five hundred fifty-five billion, three hundred fifty-five million, fifteen thousand, three hundred twenty-one".