21585139452361 has 27 divisors (see below), whose sum is σ = 23282590436679. Its totient is φ = 20007303907008.

The previous prime is 21585139452323. The next prime is 21585139452419. The reversal of 21585139452361 is 16325493158512.

It is a happy number.

The square root of 21585139452361 is 4645981.

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

It can be written as a sum of positive squares in only one way, i.e., 16805039366025 + 4780100086336 = 4099395^2 + 2186344^2 .

It is not a de Polignac number, because 21585139452361 - 2¹¹ = 21585139450313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21585139458361) 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, 5291770320 + ... + 5291774398.

Almost surely, 2^{21585139452361} is an apocalyptic number.

21585139452361 is the 4645981-st square number.

21585139452361 is the 2322991-st centered octagonal number.

It is an amenable number.

21585139452361 is a deficient number, since it is larger than the sum of its proper divisors (1697450984318).

21585139452361 is an frugal number, since it uses more digits than its factorization.

21585139452361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8326 (or 4163 counting only the distinct ones).

The product of its digits is 7776000, while the sum is 55.

The spelling of 21585139452361 in words is "twenty-one trillion, five hundred eighty-five billion, one hundred thirty-nine million, four hundred fifty-two thousand, three hundred sixty-one".