655526166521221 has 4 divisors (see below), whose sum is σ = 655614619661344. Its totient is φ = 655437713381100.

The previous prime is 655526166521207. The next prime is 655526166521257. The reversal of 655526166521221 is 122125661625556.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 655526166521221 - 2⁵ = 655526166521189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655526166521921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44226558945 + ... + 44226573766.

It is an arithmetic number, because the mean of its divisors is an integer number (163903654915336).

Almost surely, 2^{655526166521221} is an apocalyptic number.

It is an amenable number.

655526166521221 is a deficient number, since it is larger than the sum of its proper divisors (88453140123).

655526166521221 is an equidigital number, since it uses as much as digits as its factorization.

655526166521221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88453140122.

The product of its digits is 12960000, while the sum is 55.

The spelling of 655526166521221 in words is "six hundred fifty-five trillion, five hundred twenty-six billion, one hundred sixty-six million, five hundred twenty-one thousand, two hundred twenty-one".