212991 has 4 divisors (see below), whose sum is σ = 283992. Its totient is φ = 141992.

The previous prime is 212987. The next prime is 212999. The reversal of 212991 is 199212.

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

It is a cyclic number.

It is not a de Polignac number, because 212991 - 2² = 212987 is a prime.

It is an Ulam number.

It is a D-number.

It is a plaindrome in base 14 and base 16.

It is a zygodrome in base 2 and base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35496 + ... + 35501.

It is an arithmetic number, because the mean of its divisors is an integer number (70998).

2²¹²⁹⁹¹ is an apocalyptic number.

212991 is a deficient number, since it is larger than the sum of its proper divisors (71001).

212991 is an equidigital number, since it uses as much as digits as its factorization.

212991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71000.

The product of its digits is 324, while the sum is 24.

The square root of 212991 is about 461.5094798593. The cubic root of 212991 is about 59.7200850466.

The spelling of 212991 in words is "two hundred twelve thousand, nine hundred ninety-one".