21212223210 has 48 divisors (see below), whose sum is σ = 56642377896. Its totient is φ = 5503711104.

The previous prime is 21212223199. The next prime is 21212223233. The reversal of 21212223210 is 1232221212.

21212223210 is a `hidden beast` number, since 2 + 121 + 222 + 321 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 21162393729 + 49829481 = 145473^2 + 7059^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3181689 + ... + 3188348.

Almost surely, 2^21212223210 is an apocalyptic number.

21212223210 is an abundant number, since it is smaller than the sum of its proper divisors (35430154686).

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

21212223210 is a wasteful number, since it uses less digits than its factorization.

21212223210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6370087 (or 6370084 counting only the distinct ones).

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

Adding to 21212223210 its reverse (1232221212), we get a palindrome (22444444422).

The spelling of 21212223210 in words is "twenty-one billion, two hundred twelve million, two hundred twenty-three thousand, two hundred ten".