21220212210 has 32 divisors (see below), whose sum is σ = 50956577280. Its totient is φ = 5655604608.

The previous prime is 21220212179. The next prime is 21220212217. The reversal of 21220212210 is 1221202212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21220212210.

It is not an unprimeable number, because it can be changed into a prime (21220212217) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 139315 + ... + 248694.

It is an arithmetic number, because the mean of its divisors is an integer number (1592393040).

Almost surely, 2^21220212210 is an apocalyptic number.

21220212210 is an abundant number, since it is smaller than the sum of its proper divisors (29736365070).

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

21220212210 is a wasteful number, since it uses less digits than its factorization.

21220212210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389842.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21220212210 its reverse (1221202212), we get a palindrome (22441414422).

The spelling of 21220212210 in words is "twenty-one billion, two hundred twenty million, two hundred twelve thousand, two hundred ten".