21059840 has 36 divisors (see below), whose sum is σ = 50447964. Its totient is φ = 8423424.

The previous prime is 21059837. The next prime is 21059849. The reversal of 21059840 is 4895012.

It can be written as a sum of positive squares in 2 ways, for example, as 14258176 + 6801664 = 3776^2 + 2608^2 .

It is not an unprimeable number, because it can be changed into a prime (21059849) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 6947 + ... + 9506.

Almost surely, 2^21059840 is an apocalyptic number.

21059840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21059840 is an abundant number, since it is smaller than the sum of its proper divisors (29388124).

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

21059840 is an equidigital number, since it uses as much as digits as its factorization.

21059840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16474 (or 16460 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 21059840 is about 4589.1001296551. The cubic root of 21059840 is about 276.1542231260.

The spelling of 21059840 in words is "twenty-one million, fifty-nine thousand, eight hundred forty".