21101021220 has 24 divisors (see below), whose sum is σ = 59082859584. Its totient is φ = 5626938976.

The previous prime is 21101021203. The next prime is 21101021243. The reversal of 21101021220 is 2212010112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21101021196 and 21101021205.

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 7 ways as a sum of consecutive naturals, for example, 175841784 + ... + 175841903.

It is an arithmetic number, because the mean of its divisors is an integer number (2461785816).

Almost surely, 2^21101021220 is an apocalyptic number.

21101021220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21101021220 is an abundant number, since it is smaller than the sum of its proper divisors (37981838364).

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

21101021220 is a wasteful number, since it uses less digits than its factorization.

21101021220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351683699 (or 351683697 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21101021220 its reverse (2212010112), we get a palindrome (23313031332).

The spelling of 21101021220 in words is "twenty-one billion, one hundred one million, twenty-one thousand, two hundred twenty".