55190021 has 2 divisors, whose sum is σ = 55190022. Its totient is φ = 55190020.

The previous prime is 55189999. The next prime is 55190029. The reversal of 55190021 is 12009155.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53949025 + 1240996 = 7345^2 + 1114^2 .

It is a cyclic number.

It is not a de Polignac number, because 55190021 - 2¹⁰ = 55188997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55190029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27595010 + 27595011.

It is an arithmetic number, because the mean of its divisors is an integer number (27595011).

Almost surely, 2^55190021 is an apocalyptic number.

It is an amenable number.

55190021 is a deficient number, since it is larger than the sum of its proper divisors (1).

55190021 is an equidigital number, since it uses as much as digits as its factorization.

55190021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 450, while the sum is 23.

The square root of 55190021 is about 7428.9986539237. The cubic root of 55190021 is about 380.7327068031.

Adding to 55190021 its reverse (12009155), we get a palindrome (67199176).

The spelling of 55190021 in words is "fifty-five million, one hundred ninety thousand, twenty-one".