2166221653625 has 8 divisors (see below), whose sum is σ = 2703444623880. Its totient is φ = 1732977322800.

The previous prime is 2166221653613. The next prime is 2166221653699. The reversal of 2166221653625 is 5263561226612.

It can be written as a sum of positive squares in 4 ways, for example, as 177210689296 + 1989010964329 = 420964^2 + 1410323^2 .

It is not a de Polignac number, because 2166221653625 - 2⁸ = 2166221653369 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2166221653625.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8664886490 + ... + 8664886739.

It is an arithmetic number, because the mean of its divisors is an integer number (337930577985).

Almost surely, 2^{2166221653625} is an apocalyptic number.

2166221653625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

2166221653625 is a deficient number, since it is larger than the sum of its proper divisors (537222970255).

2166221653625 is an equidigital number, since it uses as much as digits as its factorization.

2166221653625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17329773244 (or 17329773234 counting only the distinct ones).

The product of its digits is 1555200, while the sum is 47.

The spelling of 2166221653625 in words is "two trillion, one hundred sixty-six billion, two hundred twenty-one million, six hundred fifty-three thousand, six hundred twenty-five".