21001020220 has 96 divisors (see below), whose sum is σ = 45688700736. Its totient is φ = 8105011200.

The previous prime is 21001020197. The next prime is 21001020223. The reversal of 21001020220 is 2202010012.

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 = 21001020197 and 21001020206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001020223) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15897160 + ... + 15898480.

It is an arithmetic number, because the mean of its divisors is an integer number (475923966).

Almost surely, 2^21001020220 is an apocalyptic number.

21001020220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001020220 is an abundant number, since it is smaller than the sum of its proper divisors (24687680516).

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

21001020220 is a wasteful number, since it uses less digits than its factorization.

21001020220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631 (or 1629 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21001020220 its reverse (2202010012), we get a palindrome (23203030232).

The spelling of 21001020220 in words is "twenty-one billion, one million, twenty thousand, two hundred twenty".