55000000021 has 2 divisors, whose sum is σ = 55000000022. Its totient is φ = 55000000020.

The previous prime is 55000000001. The next prime is 55000000039. The reversal of 55000000021 is 12000000055.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 44055911025 + 10944088996 = 209895^2 + 104614^2 .

It is a cyclic number.

It is not a de Polignac number, because 55000000021 - 2⁷ = 54999999893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 54999999938 and 55000000010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55000000001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27500000010 + 27500000011.

It is an arithmetic number, because the mean of its divisors is an integer number (27500000011).

Almost surely, 2^55000000021 is an apocalyptic number.

It is an amenable number.

55000000021 is a deficient number, since it is larger than the sum of its proper divisors (1).

55000000021 is an equidigital number, since it uses as much as digits as its factorization.

55000000021 is an evil number, because the sum of its binary digits is even.

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

Adding to 55000000021 its reverse (12000000055), we get a palindrome (67000000076).

The spelling of 55000000021 in words is "fifty-five billion, twenty-one", and thus it is an aban number and an uban number.