20561617325 has 6 divisors (see below), whose sum is σ = 25496405514. Its totient is φ = 16449293840.

The previous prime is 20561617289. The next prime is 20561617333. The reversal of 20561617325 is 52371616502.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 1323649924 + 19237967401 = 36382^2 + 138701^2 .

It is not a de Polignac number, because 20561617325 - 2¹⁰ = 20561616301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 411232322 + ... + 411232371.

It is an arithmetic number, because the mean of its divisors is an integer number (4249400919).

Almost surely, 2^20561617325 is an apocalyptic number.

20561617325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20561617325 is a deficient number, since it is larger than the sum of its proper divisors (4934788189).

20561617325 is an equidigital number, since it uses as much as digits as its factorization.

20561617325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 822464703 (or 822464698 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 38.

The spelling of 20561617325 in words is "twenty billion, five hundred sixty-one million, six hundred seventeen thousand, three hundred twenty-five".