21010221020 has 48 divisors (see below), whose sum is σ = 45658317600. Its totient is φ = 8111550720.

The previous prime is 21010220999. The next prime is 21010221053. The reversal of 21010221020 is 2012201012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21010220992 and 21010221010.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2902766 + ... + 2909994.

It is an arithmetic number, because the mean of its divisors is an integer number (951214950).

Almost surely, 2^21010221020 is an apocalyptic number.

21010221020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21010221020 is an abundant number, since it is smaller than the sum of its proper divisors (24648096580).

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

21010221020 is a wasteful number, since it uses less digits than its factorization.

21010221020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12278 (or 12276 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21010221020 its reverse (2012201012), we get a palindrome (23022422032).

The spelling of 21010221020 in words is "twenty-one billion, ten million, two hundred twenty-one thousand, twenty".