21021110197 has 2 divisors, whose sum is σ = 21021110198. Its totient is φ = 21021110196.

The previous prime is 21021110183. The next prime is 21021110239. The reversal of 21021110197 is 79101112012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19758800356 + 1262309841 = 140566^2 + 35529^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021110197 - 2¹¹ = 21021108149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021110167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510555098 + 10510555099.

It is an arithmetic number, because the mean of its divisors is an integer number (10510555099).

Almost surely, 2^21021110197 is an apocalyptic number.

It is an amenable number.

21021110197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021110197 is an equidigital number, since it uses as much as digits as its factorization.

21021110197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 25.

The spelling of 21021110197 in words is "twenty-one billion, twenty-one million, one hundred ten thousand, one hundred ninety-seven".