21000101220 has 144 divisors (see below), whose sum is σ = 75148889088. Its totient is φ = 4645175040.

The previous prime is 21000101197. The next prime is 21000101237. The reversal of 21000101220 is 2210100012.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 229759 + ... + 307878.

Almost surely, 2^21000101220 is an apocalyptic number.

21000101220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000101220 is an abundant number, since it is smaller than the sum of its proper divisors (54148787868).

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

21000101220 is a wasteful number, since it uses less digits than its factorization.

21000101220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 537690 (or 537685 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21000101220 its reverse (2210100012), we get a palindrome (23210201232).

The spelling of 21000101220 in words is "twenty-one billion, one hundred one thousand, two hundred twenty".