21001101220 has 36 divisors (see below), whose sum is σ = 48476101212. Its totient is φ = 7636763200.

The previous prime is 21001101217. The next prime is 21001101239. The reversal of 21001101220 is 2210110012.

It can be written as a sum of positive squares in 2 ways, for example, as 13132701604 + 7868399616 = 114598^2 + 88704^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21001101197 and 21001101206.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4336651 + ... + 4341490.

It is an arithmetic number, because the mean of its divisors is an integer number (1346558367).

Almost surely, 2^21001101220 is an apocalyptic number.

21001101220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001101220 is an abundant number, since it is smaller than the sum of its proper divisors (27474999992).

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

21001101220 is a wasteful number, since it uses less digits than its factorization.

21001101220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8678172 (or 8678159 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21001101220 its reverse (2210110012), we get a palindrome (23211211232).

It can be divided in two parts, 21001 and 101220, that added together give a palindrome (122221).

The spelling of 21001101220 in words is "twenty-one billion, one million, one hundred one thousand, two hundred twenty".