21715555424321 has 12 divisors (see below), whose sum is σ = 24196139088996. Its totient is φ = 19470983685120.

The previous prime is 21715555424267. The next prime is 21715555424333. The reversal of 21715555424321 is 12342455551712.

It can be written as a sum of positive squares in 2 ways, for example, as 17175719809600 + 4539835614721 = 4144360^2 + 2130689^2 .

It is not a de Polignac number, because 21715555424321 - 2³⁴ = 21698375555137 is a prime.

It is a super-2 number, since 2×21715555424321² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715555424221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1229219936 + ... + 1229237601.

It is an arithmetic number, because the mean of its divisors is an integer number (2016344924083).

Almost surely, 2^{21715555424321} is an apocalyptic number.

It is an amenable number.

21715555424321 is a deficient number, since it is larger than the sum of its proper divisors (2480583664675).

21715555424321 is a wasteful number, since it uses less digits than its factorization.

21715555424321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2458457632 (or 2458457621 counting only the distinct ones).

The product of its digits is 1680000, while the sum is 47.

The spelling of 21715555424321 in words is "twenty-one trillion, seven hundred fifteen billion, five hundred fifty-five million, four hundred twenty-four thousand, three hundred twenty-one".