20689240 has 64 divisors (see below), whose sum is σ = 54704160. Its totient is φ = 6942720.

The previous prime is 20689237. The next prime is 20689241. The reversal of 20689240 is 4298602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20689241) 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, 3912 + ... + 7528.

Almost surely, 2^20689240 is an apocalyptic number.

20689240 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 20689240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27352080).

20689240 is an abundant number, since it is smaller than the sum of its proper divisors (34014920).

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

20689240 is a wasteful number, since it uses less digits than its factorization.

20689240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3652 (or 3648 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 20689240 is about 4548.5426237422. The cubic root of 20689240 is about 274.5247549293.

The spelling of 20689240 in words is "twenty million, six hundred eighty-nine thousand, two hundred forty".