212161820 has 48 divisors (see below), whose sum is σ = 481360320. Its totient is φ = 78084096.

The previous prime is 212161813. The next prime is 212161823. The reversal of 212161820 is 28161212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212161823) 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 15 ways as a sum of consecutive naturals, for example, 92204 + ... + 94476.

It is an arithmetic number, because the mean of its divisors is an integer number (10028340).

Almost surely, 2^212161820 is an apocalyptic number.

212161820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 212161820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (240680160).

212161820 is an abundant number, since it is smaller than the sum of its proper divisors (269198500).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

212161820 is a wasteful number, since it uses less digits than its factorization.

212161820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2654 (or 2652 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 212161820 is about 14565.7756401779. The cubic root of 212161820 is about 596.4248693418.

The spelling of 212161820 in words is "two hundred twelve million, one hundred sixty-one thousand, eight hundred twenty".