55215421 has 2 divisors, whose sum is σ = 55215422. Its totient is φ = 55215420.

The previous prime is 55215389. The next prime is 55215427. The reversal of 55215421 is 12451255.

55215421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54243225 + 972196 = 7365^2 + 986^2 .

It is a cyclic number.

It is not a de Polignac number, because 55215421 - 2⁵ = 55215389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55215427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27607710 + 27607711.

It is an arithmetic number, because the mean of its divisors is an integer number (27607711).

Almost surely, 2^55215421 is an apocalyptic number.

It is an amenable number.

55215421 is a deficient number, since it is larger than the sum of its proper divisors (1).

55215421 is an equidigital number, since it uses as much as digits as its factorization.

55215421 is an odious number, because the sum of its binary digits is odd.

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

The square root of 55215421 is about 7430.7079743454. The cubic root of 55215421 is about 380.7911058119.

Adding to 55215421 its reverse (12451255), we get a palindrome (67666676).

The spelling of 55215421 in words is "fifty-five million, two hundred fifteen thousand, four hundred twenty-one".