21838840 has 32 divisors (see below), whose sum is σ = 50284080. Its totient is φ = 8531712.

The previous prime is 21838837. The next prime is 21838853. The reversal of 21838840 is 4883812.

It is a junction number, because it is equal to n+sod(n) for n = 21838796 and 21838805.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4629 + ... + 8068.

Almost surely, 2^21838840 is an apocalyptic number.

21838840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21838840 is an abundant number, since it is smaller than the sum of its proper divisors (28445240).

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

21838840 is a wasteful number, since it uses less digits than its factorization.

21838840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12751 (or 12747 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 34.

The square root of 21838840 is about 4673.2044680283. The cubic root of 21838840 is about 279.5180484653.

The spelling of 21838840 in words is "twenty-one million, eight hundred thirty-eight thousand, eight hundred forty".