20685839790 has 256 divisors, whose sum is σ = 65353236480. Its totient is φ = 4059694080.

The previous prime is 20685839789. The next prime is 20685839791. The reversal of 20685839790 is 9793858602.

It is an interprime number because it is at equal distance from previous prime (20685839789) and next prime (20685839791).

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a self number, because there is not a number n which added to its sum of digits gives 20685839790.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20685839791) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 22076202 + ... + 22077138.

It is an arithmetic number, because the mean of its divisors is an integer number (255286080).

Almost surely, 2^20685839790 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20685839790, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32676618240).

20685839790 is an abundant number, since it is smaller than the sum of its proper divisors (44667396690).

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

20685839790 is a wasteful number, since it uses less digits than its factorization.

20685839790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1487.

The product of its (nonzero) digits is 6531840, while the sum is 57.

The spelling of 20685839790 in words is "twenty billion, six hundred eighty-five million, eight hundred thirty-nine thousand, seven hundred ninety".