21210221220 has 48 divisors (see below), whose sum is σ = 59403539328. Its totient is φ = 5654638080.

The previous prime is 21210221203. The next prime is 21210221239. The reversal of 21210221220 is 2212201212.

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 21210221220.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 208305 + ... + 292935.

It is an arithmetic number, because the mean of its divisors is an integer number (1237573736).

Almost surely, 2^21210221220 is an apocalyptic number.

21210221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210221220 is an abundant number, since it is smaller than the sum of its proper divisors (38193318108).

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

21210221220 is a wasteful number, since it uses less digits than its factorization.

21210221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88820 (or 88818 counting only the distinct ones).

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

Adding to 21210221220 its reverse (2212201212), we get a palindrome (23422422432).

The spelling of 21210221220 in words is "twenty-one billion, two hundred ten million, two hundred twenty-one thousand, two hundred twenty".