211979997 has 10 divisors (see below), whose sum is σ = 316661598. Its totient is φ = 141319944.

The previous prime is 211979959. The next prime is 211980001. The reversal of 211979997 is 799979112.

It can be written as a sum of positive squares in only one way, i.e., 199911321 + 12068676 = 14139^2 + 3474^2 .

It is not a de Polignac number, because 211979997 - 2⁷ = 211979869 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211979927) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1308438 + ... + 1308599.

Almost surely, 2^211979997 is an apocalyptic number.

211979997 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

211979997 is a deficient number, since it is larger than the sum of its proper divisors (104681601).

211979997 is an equidigital number, since it uses as much as digits as its factorization.

211979997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2617049 (or 2617040 counting only the distinct ones).

The product of its digits is 642978, while the sum is 54.

The square root of 211979997 is about 14559.5328565171. The cubic root of 211979997 is about 596.2544416425.

The spelling of 211979997 in words is "two hundred eleven million, nine hundred seventy-nine thousand, nine hundred ninety-seven".