555131221 has 2 divisors, whose sum is σ = 555131222. Its totient is φ = 555131220.

The previous prime is 555131207. The next prime is 555131257. The reversal of 555131221 is 122131555.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 379860100 + 175271121 = 19490^2 + 13239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-555131221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (555137221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 277565610 + 277565611.

It is an arithmetic number, because the mean of its divisors is an integer number (277565611).

Almost surely, 2^555131221 is an apocalyptic number.

It is an amenable number.

555131221 is a deficient number, since it is larger than the sum of its proper divisors (1).

555131221 is an equidigital number, since it uses as much as digits as its factorization.

555131221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1500, while the sum is 25.

The square root of 555131221 is about 23561.2228248026. Note that the first 3 decimals coincide. The cubic root of 555131221 is about 821.8613383321.

Adding to 555131221 its reverse (122131555), we get a palindrome (677262776).

The spelling of 555131221 in words is "five hundred fifty-five million, one hundred thirty-one thousand, two hundred twenty-one".