55213121 has 4 divisors (see below), whose sum is σ = 56254932. Its totient is φ = 54171312.

The previous prime is 55213111. The next prime is 55213141. The reversal of 55213121 is 12131255.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 22848400 + 32364721 = 4780^2 + 5689^2 .

It is a cyclic number.

It is not a de Polignac number, because 55213121 - 2¹⁸ = 54950977 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 55213093 and 55213102.

It is not an unprimeable number, because it can be changed into a prime (55213111) 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, 520826 + ... + 520931.

It is an arithmetic number, because the mean of its divisors is an integer number (14063733).

Almost surely, 2^55213121 is an apocalyptic number.

It is an amenable number.

55213121 is a deficient number, since it is larger than the sum of its proper divisors (1041811).

55213121 is a wasteful number, since it uses less digits than its factorization.

55213121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1041810.

The product of its digits is 300, while the sum is 20.

The square root of 55213121 is about 7430.5532095531. The cubic root of 55213121 is about 380.7858184502.

Adding to 55213121 its reverse (12131255), we get a palindrome (67344376).

The spelling of 55213121 in words is "fifty-five million, two hundred thirteen thousand, one hundred twenty-one".