211891997 has 2 divisors, whose sum is σ = 211891998. Its totient is φ = 211891996.

The previous prime is 211891987. The next prime is 211892011. The reversal of 211891997 is 799198112.

211891997 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 176916601 + 34975396 = 13301^2 + 5914^2 .

It is a cyclic number.

It is not a de Polignac number, because 211891997 - 2⁸ = 211891741 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211891907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105945998 + 105945999.

It is an arithmetic number, because the mean of its divisors is an integer number (105945999).

Almost surely, 2^211891997 is an apocalyptic number.

It is an amenable number.

211891997 is a deficient number, since it is larger than the sum of its proper divisors (1).

211891997 is an equidigital number, since it uses as much as digits as its factorization.

211891997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81648, while the sum is 47.

The square root of 211891997 is about 14556.5104678285. The cubic root of 211891997 is about 596.1719218230.

The spelling of 211891997 in words is "two hundred eleven million, eight hundred ninety-one thousand, nine hundred ninety-seven".