21110020 has 12 divisors (see below), whose sum is σ = 44331084. Its totient is φ = 8444000.

The previous prime is 21109987. The next prime is 21110027. The reversal of 21110020 is 2001112.

It can be written as a sum of positive squares in 2 ways, for example, as 7918596 + 13191424 = 2814^2 + 3632^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21109985 and 21110012.

It is not an unprimeable number, because it can be changed into a prime (21110027) 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, 527731 + ... + 527770.

It is an arithmetic number, because the mean of its divisors is an integer number (3694257).

Almost surely, 2^21110020 is an apocalyptic number.

21110020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21110020 is an abundant number, since it is smaller than the sum of its proper divisors (23221064).

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

21110020 is a wasteful number, since it uses less digits than its factorization.

21110020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1055510 (or 1055508 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21110020 is about 4594.5641795496. The cubic root of 21110020 is about 276.3733831842.

Adding to 21110020 its reverse (2001112), we get a palindrome (23111132).

The spelling of 21110020 in words is "twenty-one million, one hundred ten thousand, twenty".