21110221020 has 48 divisors (see below), whose sum is σ = 67552708608. Its totient is φ = 4825193280.

The previous prime is 21110221009. The next prime is 21110221037. The reversal of 21110221020 is 2012201112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21110220987 and 21110221005.

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, 25130796 + ... + 25131635.

It is an arithmetic number, because the mean of its divisors is an integer number (1407348096).

Almost surely, 2^21110221020 is an apocalyptic number.

21110221020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21110221020 is an abundant number, since it is smaller than the sum of its proper divisors (46442487588).

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

21110221020 is a wasteful number, since it uses less digits than its factorization.

21110221020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50262450 (or 50262448 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21110221020 its reverse (2012201112), we get a palindrome (23122422132).

The spelling of 21110221020 in words is "twenty-one billion, one hundred ten million, two hundred twenty-one thousand, twenty".