55212721 has 4 divisors (see below), whose sum is σ = 55432944. Its totient is φ = 54992500.

The previous prime is 55212713. The next prime is 55212737. The reversal of 55212721 is 12721255.

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 not a de Polignac number, because 55212721 - 2³ = 55212713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55219721) 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, 109735 + ... + 110236.

It is an arithmetic number, because the mean of its divisors is an integer number (13858236).

Almost surely, 2^55212721 is an apocalyptic number.

It is an amenable number.

55212721 is a deficient number, since it is larger than the sum of its proper divisors (220223).

55212721 is a wasteful number, since it uses less digits than its factorization.

55212721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220222.

The product of its digits is 1400, while the sum is 25.

The square root of 55212721 is about 7430.5262936080. The cubic root of 55212721 is about 380.7848988940.

Adding to 55212721 its reverse (12721255), we get a palindrome (67933976).

The spelling of 55212721 in words is "fifty-five million, two hundred twelve thousand, seven hundred twenty-one".