21010505213 has 2 divisors, whose sum is σ = 21010505214. Its totient is φ = 21010505212.

The previous prime is 21010505203. The next prime is 21010505297. The reversal of 21010505213 is 31250501012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17631059524 + 3379445689 = 132782^2 + 58133^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010505213 - 2⁶ = 21010505149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21010505203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505252606 + 10505252607.

It is an arithmetic number, because the mean of its divisors is an integer number (10505252607).

Almost surely, 2^21010505213 is an apocalyptic number.

It is an amenable number.

21010505213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010505213 is an equidigital number, since it uses as much as digits as its factorization.

21010505213 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 21010505213 in words is "twenty-one billion, ten million, five hundred five thousand, two hundred thirteen".