21201420210 has 64 divisors (see below), whose sum is σ = 52174281600. Its totient is φ = 5510545920.

The previous prime is 21201420197. The next prime is 21201420221. The reversal of 21201420210 is 1202410212.

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

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21201420210.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1373616 + ... + 1388964.

It is an arithmetic number, because the mean of its divisors is an integer number (815223150).

Almost surely, 2^21201420210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21201420210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26087140800).

21201420210 is an abundant number, since it is smaller than the sum of its proper divisors (30972861390).

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

21201420210 is a wasteful number, since it uses less digits than its factorization.

21201420210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16523.

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

Adding to 21201420210 its reverse (1202410212), we get a palindrome (22403830422).

The spelling of 21201420210 in words is "twenty-one billion, two hundred one million, four hundred twenty thousand, two hundred ten".