21221202210 has 128 divisors (see below), whose sum is σ = 57054412800. Its totient is φ = 5016211200.

The previous prime is 21221202203. The next prime is 21221202229. The reversal of 21221202210 is 1220212212.

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 21221202210.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1577091 + ... + 1590489.

It is an arithmetic number, because the mean of its divisors is an integer number (445737600).

Almost surely, 2^21221202210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21221202210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28527206400).

21221202210 is an abundant number, since it is smaller than the sum of its proper divisors (35833210590).

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

21221202210 is a wasteful number, since it uses less digits than its factorization.

21221202210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13584.

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

Adding to 21221202210 its reverse (1220212212), we get a palindrome (22441414422).

The spelling of 21221202210 in words is "twenty-one billion, two hundred twenty-one million, two hundred two thousand, two hundred ten".