55415221 has 2 divisors, whose sum is σ = 55415222. Its totient is φ = 55415220.

The previous prime is 55415207. The next prime is 55415251. The reversal of 55415221 is 12251455.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52562500 + 2852721 = 7250^2 + 1689^2 .

It is a cyclic number.

It is not a de Polignac number, because 55415221 - 2⁷ = 55415093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55415251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27707610 + 27707611.

It is an arithmetic number, because the mean of its divisors is an integer number (27707611).

Almost surely, 2^55415221 is an apocalyptic number.

It is an amenable number.

55415221 is a deficient number, since it is larger than the sum of its proper divisors (1).

55415221 is an equidigital number, since it uses as much as digits as its factorization.

55415221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2000, while the sum is 25.

The square root of 55415221 is about 7444.1400443570. The cubic root of 55415221 is about 381.2498573501.

Adding to 55415221 its reverse (12251455), we get a palindrome (67666676).

The spelling of 55415221 in words is "fifty-five million, four hundred fifteen thousand, two hundred twenty-one".