21146563565 has 8 divisors (see below), whose sum is σ = 26061711000. Its totient is φ = 16460027712.

The previous prime is 21146563553. The next prime is 21146563567. The reversal of 21146563565 is 56536564112.

It can be written as a sum of positive squares in 4 ways, for example, as 1343882281 + 19802681284 = 36659^2 + 140722^2 .

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 21146563565 - 2⁸ = 21146563309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21146563567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57152690 + ... + 57153059.

It is an arithmetic number, because the mean of its divisors is an integer number (3257713875).

Almost surely, 2^21146563565 is an apocalyptic number.

It is an amenable number.

21146563565 is a deficient number, since it is larger than the sum of its proper divisors (4915147435).

21146563565 is a wasteful number, since it uses less digits than its factorization.

21146563565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114305791.

The product of its digits is 648000, while the sum is 44.

The spelling of 21146563565 in words is "twenty-one billion, one hundred forty-six million, five hundred sixty-three thousand, five hundred sixty-five".