212721 has 16 divisors (see below), whose sum is σ = 310464. Its totient is φ = 129024.

The previous prime is 212701. The next prime is 212777. The reversal of 212721 is 127212.

It is not a de Polignac number, because 212721 - 2⁷ = 212593 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

212721 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 212721.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 212721.

It is not an unprimeable number, because it can be changed into a prime (212701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2145 + ... + 2241.

It is an arithmetic number, because the mean of its divisors is an integer number (19404).

2²¹²⁷²¹ is an apocalyptic number.

It is an amenable number.

212721 is a deficient number, since it is larger than the sum of its proper divisors (97743).

212721 is a wasteful number, since it uses less digits than its factorization.

212721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160.

The product of its digits is 56, while the sum is 15.

The square root of 212721 is about 461.2168687288. The cubic root of 212721 is about 59.6948394710.

Adding to 212721 its reverse (127212), we get a palindrome (339933).

The spelling of 212721 in words is "two hundred twelve thousand, seven hundred twenty-one", and thus it is an iban number.