55213021 has 4 divisors (see below), whose sum is σ = 55912000. Its totient is φ = 54514044.

The previous prime is 55213007. The next prime is 55213027. The reversal of 55213021 is 12031255.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55213021 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 55213021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55213027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 349371 + ... + 349528.

It is an arithmetic number, because the mean of its divisors is an integer number (13978000).

Almost surely, 2^55213021 is an apocalyptic number.

It is an amenable number.

55213021 is a deficient number, since it is larger than the sum of its proper divisors (698979).

55213021 is an equidigital number, since it uses as much as digits as its factorization.

55213021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 698978.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 55213021 is about 7430.5464805760. The cubic root of 55213021 is about 380.7855885616.

Adding to 55213021 its reverse (12031255), we get a palindrome (67244276).

The spelling of 55213021 in words is "fifty-five million, two hundred thirteen thousand, twenty-one".