212113721 has 4 divisors (see below), whose sum is σ = 214669392. Its totient is φ = 209558052.

The previous prime is 212113717. The next prime is 212113753. The reversal of 212113721 is 127311212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 212113721 - 2² = 212113717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 212113693 and 212113702.

It is not an unprimeable number, because it can be changed into a prime (212113621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1277711 + ... + 1277876.

It is an arithmetic number, because the mean of its divisors is an integer number (53667348).

Almost surely, 2^212113721 is an apocalyptic number.

It is an amenable number.

212113721 is a deficient number, since it is larger than the sum of its proper divisors (2555671).

212113721 is an equidigital number, since it uses as much as digits as its factorization.

212113721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2555670.

The product of its digits is 168, while the sum is 20.

The square root of 212113721 is about 14564.1244501686. The cubic root of 212113721 is about 596.3797943012.

Adding to 212113721 its reverse (127311212), we get a palindrome (339424933).

The spelling of 212113721 in words is "two hundred twelve million, one hundred thirteen thousand, seven hundred twenty-one".