21213021210 has 128 divisors (see below), whose sum is σ = 55088916480. Its totient is φ = 5211714816.

The previous prime is 21213021191. The next prime is 21213021251. The reversal of 21213021210 is 1212031212.

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 21213021210.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 10464217 + ... + 10466243.

It is an arithmetic number, because the mean of its divisors is an integer number (430382160).

Almost surely, 2^21213021210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21213021210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27544458240).

21213021210 is an abundant number, since it is smaller than the sum of its proper divisors (33875895270).

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

21213021210 is a wasteful number, since it uses less digits than its factorization.

21213021210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2612.

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21213021210 its reverse (1212031212), we get a palindrome (22425052422).

The spelling of 21213021210 in words is "twenty-one billion, two hundred thirteen million, twenty-one thousand, two hundred ten".