21210805259361 has 27 divisors (see below), whose sum is σ = 31731336363961. Its totient is φ = 13652674211904.

The previous prime is 21210805259263. The next prime is 21210805259417. The reversal of 21210805259361 is 16395250801212.

The square root of 21210805259361 is 4605519.

It is a perfect power (a square), and thus also a powerful number.

21210805259361 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 0 + 8 + 0 + 52 + 593 + 6 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1258109939025 + 19952695320336 = 1121655^2 + 4466844^2 .

It is not a de Polignac number, because 21210805259361 - 2²¹ = 21210803162209 is a prime.

It is a super-3 number, since 3×21210805259361³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210805239361) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 400653685 + ... + 400706621.

Almost surely, 2^{21210805259361} is an apocalyptic number.

21210805259361 is the 4605519-th square number.

21210805259361 is the 2302760-th centered octagonal number.

It is an amenable number.

21210805259361 is a deficient number, since it is larger than the sum of its proper divisors (10520531104600).

21210805259361 is an frugal number, since it uses more digits than its factorization.

21210805259361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105938 (or 52969 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The spelling of 21210805259361 in words is "twenty-one trillion, two hundred ten billion, eight hundred five million, two hundred fifty-nine thousand, three hundred sixty-one".