20685940 has 48 divisors (see below), whose sum is σ = 50186304. Its totient is φ = 7078400.

The previous prime is 20685919. The next prime is 20685971. The reversal of 20685940 is 4958602.

It is a happy number.

It is a super-2 number, since 2×20685940² = 855816227367200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a junction number, because it is equal to n+sod(n) for n = 20685896 and 20685905.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 975 + ... + 6505.

It is an arithmetic number, because the mean of its divisors is an integer number (1045548).

Almost surely, 2^20685940 is an apocalyptic number.

20685940 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 20685940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25093152).

20685940 is an abundant number, since it is smaller than the sum of its proper divisors (29500364).

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

20685940 is a wasteful number, since it uses less digits than its factorization.

20685940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5568 (or 5566 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 20685940 is about 4548.1798557225. The cubic root of 20685940 is about 274.5101582942.

It can be divided in two parts, 2068 and 5940, that added together give a palindrome (8008).

The spelling of 20685940 in words is "twenty million, six hundred eighty-five thousand, nine hundred forty".