55442021 has 4 divisors (see below), whose sum is σ = 56940492. Its totient is φ = 53943552.

The previous prime is 55442017. The next prime is 55442033. The reversal of 55442021 is 12024455.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12024455 = 5 ⋅2404891.

It can be written as a sum of positive squares in 2 ways, for example, as 53085796 + 2356225 = 7286^2 + 1535^2 .

It is a cyclic number.

It is not a de Polignac number, because 55442021 - 2² = 55442017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55442011) 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, 749180 + ... + 749253.

It is an arithmetic number, because the mean of its divisors is an integer number (14235123).

Almost surely, 2^55442021 is an apocalyptic number.

It is an amenable number.

55442021 is a deficient number, since it is larger than the sum of its proper divisors (1498471).

55442021 is a wasteful number, since it uses less digits than its factorization.

55442021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1498470.

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 55442021 is about 7445.9399003752. The cubic root of 55442021 is about 381.3113076719.

Adding to 55442021 its reverse (12024455), we get a palindrome (67466476).

The spelling of 55442021 in words is "fifty-five million, four hundred forty-two thousand, twenty-one".