55123021 has 4 divisors (see below), whose sum is σ = 56163132. Its totient is φ = 54082912.

The previous prime is 55123001. The next prime is 55123037. The reversal of 55123021 is 12032155.

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 44488900 + 10634121 = 6670^2 + 3261^2 .

It is a cyclic number.

It is not a de Polignac number, because 55123021 - 2⁵ = 55122989 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 55123021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55123001) 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, 519976 + ... + 520081.

It is an arithmetic number, because the mean of its divisors is an integer number (14040783).

Almost surely, 2^55123021 is an apocalyptic number.

It is an amenable number.

55123021 is a deficient number, since it is larger than the sum of its proper divisors (1040111).

55123021 is a wasteful number, since it uses less digits than its factorization.

55123021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1040110.

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

The square root of 55123021 is about 7424.4879284702. The cubic root of 55123021 is about 380.5785761563.

Adding to 55123021 its reverse (12032155), we get a palindrome (67155176).

The spelling of 55123021 in words is "fifty-five million, one hundred twenty-three thousand, twenty-one".