212318821 has 36 divisors (see below), whose sum is σ = 260832684. Its totient is φ = 171642240.

The previous prime is 212318807. The next prime is 212318833. The reversal of 212318821 is 128813212.

It can be written as a sum of positive squares in 2 ways, for example, as 72488196 + 139830625 = 8514^2 + 11825^2 .

It is a de Polignac number, because none of the positive numbers 2^k-212318821 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 212318821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212318801) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2908441 + ... + 2908513.

Almost surely, 2^212318821 is an apocalyptic number.

It is an amenable number.

212318821 is a deficient number, since it is larger than the sum of its proper divisors (48513863).

212318821 is a wasteful number, since it uses less digits than its factorization.

212318821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194 (or 140 counting only the distinct ones).

The product of its digits is 1536, while the sum is 28.

The square root of 212318821 is about 14571.1640235089. The cubic root of 212318821 is about 596.5719523758.

The spelling of 212318821 in words is "two hundred twelve million, three hundred eighteen thousand, eight hundred twenty-one".