21170852221 has 2 divisors, whose sum is σ = 21170852222. Its totient is φ = 21170852220.

The previous prime is 21170852203. The next prime is 21170852303. The reversal of 21170852221 is 12225807112.

21170852221 = 102885² + 102886².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10585528996 + 10585323225 = 102886^2 + 102885^2 .

It is a cyclic number.

It is not a de Polignac number, because 21170852221 - 2⁵ = 21170852189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21170852621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585426110 + 10585426111.

It is an arithmetic number, because the mean of its divisors is an integer number (10585426111).

Almost surely, 2^21170852221 is an apocalyptic number.

21170852221 is the 102886-th centered square number.

It is an amenable number.

21170852221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21170852221 is an equidigital number, since it uses as much as digits as its factorization.

21170852221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4480, while the sum is 31.

The spelling of 21170852221 in words is "twenty-one billion, one hundred seventy million, eight hundred fifty-two thousand, two hundred twenty-one".