212312561 has 4 divisors (see below), whose sum is σ = 214373952. Its totient is φ = 210251172.

The previous prime is 212312537. The next prime is 212312591. The reversal of 212312561 is 165213212.

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 a de Polignac number, because none of the positive numbers 2^k-212312561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (212312591) 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, 1030541 + ... + 1030746.

It is an arithmetic number, because the mean of its divisors is an integer number (53593488).

Almost surely, 2^212312561 is an apocalyptic number.

It is an amenable number.

212312561 is a deficient number, since it is larger than the sum of its proper divisors (2061391).

212312561 is a wasteful number, since it uses less digits than its factorization.

212312561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2061390.

The product of its digits is 720, while the sum is 23.

The square root of 212312561 is about 14570.9492141041. The cubic root of 212312561 is about 596.5660892166.

Adding to 212312561 its reverse (165213212), we get a palindrome (377525773).

The spelling of 212312561 in words is "two hundred twelve million, three hundred twelve thousand, five hundred sixty-one".