212221620 has 144 divisors (see below), whose sum is σ = 719147520. Its totient is φ = 52223616.

The previous prime is 212221613. The next prime is 212221649. The reversal of 212221620 is 26122212.

212221620 is a `hidden beast` number, since 2 + 1 + 22 + 21 + 620 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 212221593 and 212221602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 61501 + ... + 64859.

It is an arithmetic number, because the mean of its divisors is an integer number (4994080).

Almost surely, 2^212221620 is an apocalyptic number.

212221620 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 212221620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (359573760).

212221620 is an abundant number, since it is smaller than the sum of its proper divisors (506925900).

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

212221620 is a wasteful number, since it uses less digits than its factorization.

212221620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3396 (or 3382 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 212221620 is about 14567.8282526944. The cubic root of 212221620 is about 596.4809002474.

Adding to 212221620 its reverse (26122212), we get a palindrome (238343832).

The spelling of 212221620 in words is "two hundred twelve million, two hundred twenty-one thousand, six hundred twenty".