655501221 has 8 divisors (see below), whose sum is σ = 971112960. Its totient is φ = 437000796.

The previous prime is 655501207. The next prime is 655501241. The reversal of 655501221 is 122105556.

655501221 is a `hidden beast` number, since 655 + 5 + 0 + 1 + 2 + 2 + 1 = 666.

It is not a de Polignac number, because 655501221 - 2¹⁵ = 655468453 is a prime.

It is a super-3 number, since 3×655501221³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 24277823 = 655501221 / (6 + 5 + 5 + 5 + 0 + 1 + 2 + 2 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655501201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12138885 + ... + 12138938.

It is an arithmetic number, because the mean of its divisors is an integer number (121389120).

Almost surely, 2^655501221 is an apocalyptic number.

It is an amenable number.

655501221 is a deficient number, since it is larger than the sum of its proper divisors (315611739).

655501221 is a wasteful number, since it uses less digits than its factorization.

655501221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24277832 (or 24277826 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The square root of 655501221 is about 25602.7580740826. The cubic root of 655501221 is about 868.6760242308.

Adding to 655501221 its reverse (122105556), we get a palindrome (777606777).

The spelling of 655501221 in words is "six hundred fifty-five million, five hundred one thousand, two hundred twenty-one".