21013201220 has 72 divisors (see below), whose sum is σ = 51357304152. Its totient is φ = 7191669760.

The previous prime is 21013201207. The next prime is 21013201241. The reversal of 21013201220 is 2210231012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7479136324 + 13534064896 = 86482^2 + 116336^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21013201195 and 21013201204.

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 23 ways as a sum of consecutive naturals, for example, 214247 + ... + 296526.

It is an arithmetic number, because the mean of its divisors is an integer number (713295891).

Almost surely, 2^21013201220 is an apocalyptic number.

21013201220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21013201220 is an abundant number, since it is smaller than the sum of its proper divisors (30344102932).

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

21013201220 is a wasteful number, since it uses less digits than its factorization.

21013201220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510821 (or 510808 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21013201220 its reverse (2210231012), we get a palindrome (23223432232).

The spelling of 21013201220 in words is "twenty-one billion, thirteen million, two hundred one thousand, two hundred twenty".