21111197 has 2 divisors, whose sum is σ = 21111198. Its totient is φ = 21111196.

The previous prime is 21111191. The next prime is 21111199. The reversal of 21111197 is 79111112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20894041 + 217156 = 4571^2 + 466^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111197 - 2¹² = 21107101 is a prime.

Together with 21111199, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555598 + 10555599.

It is an arithmetic number, because the mean of its divisors is an integer number (10555599).

Almost surely, 2^21111197 is an apocalyptic number.

It is an amenable number.

21111197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111197 is an equidigital number, since it uses as much as digits as its factorization.

21111197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 126, while the sum is 23.

The square root of 21111197 is about 4594.6922639063. The cubic root of 21111197 is about 276.3785195354.

The spelling of 21111197 in words is "twenty-one million, one hundred eleven thousand, one hundred ninety-seven".