21024221020 has 96 divisors (see below), whose sum is σ = 48899450880. Its totient is φ = 7529034240.

The previous prime is 21024221017. The next prime is 21024221027. The reversal of 21024221020 is 2012242012.

It is a junction number, because it is equal to n+sod(n) for n = 21024220985 and 21024221003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21024221027) 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, 7941337 + ... + 7943983.

It is an arithmetic number, because the mean of its divisors is an integer number (509369280).

Almost surely, 2^21024221020 is an apocalyptic number.

21024221020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21024221020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24449725440).

21024221020 is an abundant number, since it is smaller than the sum of its proper divisors (27875229860).

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

21024221020 is a wasteful number, since it uses less digits than its factorization.

21024221020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3203 (or 3201 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21024221020 its reverse (2012242012), we get a palindrome (23036463032).

The spelling of 21024221020 in words is "twenty-one billion, twenty-four million, two hundred twenty-one thousand, twenty".