55221213 has 4 divisors (see below), whose sum is σ = 73628288. Its totient is φ = 36814140.

The previous prime is 55221209. The next prime is 55221217. The reversal of 55221213 is 31212255.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (55221209) and next prime (55221217).

It is not a de Polignac number, because 55221213 - 2² = 55221209 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 55221213.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55221217) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9203533 + ... + 9203538.

It is an arithmetic number, because the mean of its divisors is an integer number (18407072).

Almost surely, 2^55221213 is an apocalyptic number.

It is an amenable number.

55221213 is a deficient number, since it is larger than the sum of its proper divisors (18407075).

55221213 is a wasteful number, since it uses less digits than its factorization.

55221213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18407074.

The product of its digits is 600, while the sum is 21.

The square root of 55221213 is about 7431.0976981870. The cubic root of 55221213 is about 380.8044201175.

Adding to 55221213 its reverse (31212255), we get a palindrome (86433468).

The spelling of 55221213 in words is "fifty-five million, two hundred twenty-one thousand, two hundred thirteen".