20829840 has 80 divisors (see below), whose sum is σ = 65025600. Its totient is φ = 5515776.

The previous prime is 20829839. The next prime is 20829841. The reversal of 20829840 is 4892802.

It is an interprime number because it is at equal distance from previous prime (20829839) and next prime (20829841).

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (20829841) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 54771 + ... + 55149.

It is an arithmetic number, because the mean of its divisors is an integer number (812820).

Almost surely, 2^20829840 is an apocalyptic number.

20829840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20829840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32512800).

20829840 is an abundant number, since it is smaller than the sum of its proper divisors (44195760).

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

20829840 is a wasteful number, since it uses less digits than its factorization.

20829840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624 (or 618 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 20829840 is about 4563.9719543398. The cubic root of 20829840 is about 275.1452235715.

The spelling of 20829840 in words is "twenty million, eight hundred twenty-nine thousand, eight hundred forty".