21152206334565 has 24 divisors (see below), whose sum is σ = 38820519862488. Its totient is φ = 10617578081280.

The previous prime is 21152206334551. The next prime is 21152206334573. The reversal of 21152206334565 is 56543360225112.

21152206334565 is a `hidden beast` number, since 2 + 1 + 1 + 5 + 2 + 2 + 0 + 633 + 4 + 5 + 6 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 423726789249 + 20728479545316 = 650943^2 + 4552854^2 .

It is not a de Polignac number, because 21152206334565 - 2⁴ = 21152206334549 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21152206334565.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13824970696 + ... + 13824972225.

It is an arithmetic number, because the mean of its divisors is an integer number (1617521660937).

Almost surely, 2^{21152206334565} is an apocalyptic number.

It is an amenable number.

21152206334565 is a deficient number, since it is larger than the sum of its proper divisors (17668313527923).

21152206334565 is a wasteful number, since it uses less digits than its factorization.

21152206334565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27649942949 (or 27649942946 counting only the distinct ones).

The product of its (nonzero) digits is 1296000, while the sum is 45.

Adding to 21152206334565 its reverse (56543360225112), we get a palindrome (77695566559677).

The spelling of 21152206334565 in words is "twenty-one trillion, one hundred fifty-two billion, two hundred six million, three hundred thirty-four thousand, five hundred sixty-five".