21222020 has 12 divisors (see below), whose sum is σ = 44566284. Its totient is φ = 8488800.

The previous prime is 21222013. The next prime is 21222023. The reversal of 21222020 is 2022212.

It can be written as a sum of positive squares in 2 ways, for example, as 12730624 + 8491396 = 3568^2 + 2914^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21221992 and 21222010.

It is not an unprimeable number, because it can be changed into a prime (21222023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530531 + ... + 530570.

It is an arithmetic number, because the mean of its divisors is an integer number (3713857).

Almost surely, 2^21222020 is an apocalyptic number.

21222020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21222020 is an abundant number, since it is smaller than the sum of its proper divisors (23344264).

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

21222020 is a wasteful number, since it uses less digits than its factorization.

21222020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061110 (or 1061108 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21222020 is about 4606.7363718798. The cubic root of 21222020 is about 276.8612910985.

Adding to 21222020 its reverse (2022212), we get a palindrome (23244232).

The spelling of 21222020 in words is "twenty-one million, two hundred twenty-two thousand, twenty".