20840680 has 96 divisors (see below), whose sum is σ = 56471040. Its totient is φ = 6914880.

The previous prime is 20840653. The next prime is 20840683. The reversal of 20840680 is 8604802.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20840683) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 672265 + ... + 672295.

It is an arithmetic number, because the mean of its divisors is an integer number (588240).

Almost surely, 2^20840680 is an apocalyptic number.

20840680 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 20840680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28235520).

20840680 is an abundant number, since it is smaller than the sum of its proper divisors (35630360).

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

20840680 is an frugal number, since it uses more digits than its factorization.

20840680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 28.

The square root of 20840680 is about 4565.1593619500. The cubic root of 20840680 is about 275.1929444851.

The spelling of 20840680 in words is "twenty million, eight hundred forty thousand, six hundred eighty".