55000021 has 4 divisors (see below), whose sum is σ = 55038592. Its totient is φ = 54961452.

The previous prime is 55000013. The next prime is 55000027. The reversal of 55000021 is 12000055.

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 55000021 - 2³ = 55000013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 54999965 and 55000010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55000027) 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, 17061 + ... + 20026.

It is an arithmetic number, because the mean of its divisors is an integer number (13759648).

Almost surely, 2^55000021 is an apocalyptic number.

It is an amenable number.

55000021 is a deficient number, since it is larger than the sum of its proper divisors (38571).

55000021 is a wasteful number, since it uses less digits than its factorization.

55000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38570.

The product of its (nonzero) digits is 50, while the sum is 13.

The square root of 55000021 is about 7416.1999029152. The cubic root of 55000021 is about 380.2952944773.

Adding to 55000021 its reverse (12000055), we get a palindrome (67000076).

The spelling of 55000021 in words is "fifty-five million, twenty-one", and thus it is an aban number and an uban number.