21112020 has 72 divisors (see below), whose sum is σ = 65277576. Its totient is φ = 5521152.

The previous prime is 21112019. The next prime is 21112031. The reversal of 21112020 is 2021112.

It can be written as a sum of positive squares in 4 ways, for example, as 10575504 + 10536516 = 3252^2 + 3246^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21111993 and 21112011.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8434 + ... + 10646.

It is an arithmetic number, because the mean of its divisors is an integer number (906633).

Almost surely, 2^21112020 is an apocalyptic number.

21112020 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 21112020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32638788).

21112020 is an abundant number, since it is smaller than the sum of its proper divisors (44165556).

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

21112020 is a wasteful number, since it uses less digits than its factorization.

21112020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2281 (or 2276 counting only the distinct ones).

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

The square root of 21112020 is about 4594.7818228943. The cubic root of 21112020 is about 276.3821109402.

Adding to 21112020 its reverse (2021112), we get a palindrome (23133132).

The spelling of 21112020 in words is "twenty-one million, one hundred twelve thousand, twenty".