21903020 has 24 divisors (see below), whose sum is σ = 47119968. Its totient is φ = 8547200.

The previous prime is 21903017. The next prime is 21903031. The reversal of 21903020 is 2030912.

It is a self number, because there is not a number n which added to its sum of digits gives 21903020.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12536 + ... + 14175.

It is an arithmetic number, because the mean of its divisors is an integer number (1963332).

Almost surely, 2^21903020 is an apocalyptic number.

21903020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21903020 is an abundant number, since it is smaller than the sum of its proper divisors (25216948).

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

21903020 is a wasteful number, since it uses less digits than its factorization.

21903020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26761 (or 26759 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 21903020 is about 4680.0662388475. The cubic root of 21903020 is about 279.7915966250.

Adding to 21903020 its reverse (2030912), we get a palindrome (23933932).

The spelling of 21903020 in words is "twenty-one million, nine hundred three thousand, twenty".