21120020 has 24 divisors (see below), whose sum is σ = 46687200. Its totient is φ = 8003232.

The previous prime is 21120019. The next prime is 21120041. The reversal of 21120020 is 2002112.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27410 + ... + 28169.

It is an arithmetic number, because the mean of its divisors is an integer number (1945300).

Almost surely, 2^21120020 is an apocalyptic number.

21120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21120020 is an abundant number, since it is smaller than the sum of its proper divisors (25567180).

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

21120020 is a wasteful number, since it uses less digits than its factorization.

21120020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55607 (or 55605 counting only the distinct ones).

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

The square root of 21120020 is about 4595.6522932006. The cubic root of 21120020 is about 276.4170164532.

Adding to 21120020 its reverse (2002112), we get a palindrome (23122132).

The spelling of 21120020 in words is "twenty-one million, one hundred twenty thousand, twenty".