211997705 has 4 divisors (see below), whose sum is σ = 254397252. Its totient is φ = 169598160.

The previous prime is 211997663. The next prime is 211997707. The reversal of 211997705 is 507799112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43309561 + 168688144 = 6581^2 + 12988^2 .

It is not a de Polignac number, because 211997705 - 2⁸ = 211997449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (211997707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21199766 + ... + 21199775.

It is an arithmetic number, because the mean of its divisors is an integer number (63599313).

Almost surely, 2^211997705 is an apocalyptic number.

It is an amenable number.

211997705 is a deficient number, since it is larger than the sum of its proper divisors (42399547).

211997705 is an equidigital number, since it uses as much as digits as its factorization.

211997705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42399546.

The product of its (nonzero) digits is 39690, while the sum is 41.

The square root of 211997705 is about 14560.1409677242. The cubic root of 211997705 is about 596.2710441204.

The spelling of 211997705 in words is "two hundred eleven million, nine hundred ninety-seven thousand, seven hundred five".