20309009256 has 128 divisors (see below), whose sum is σ = 61431120000. Its totient is φ = 6192184320.

The previous prime is 20309009243. The next prime is 20309009299. The reversal of 20309009256 is 65290090302.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20309009256.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33696 + ... + 204336.

It is an arithmetic number, because the mean of its divisors is an integer number (479930625).

Almost surely, 2^20309009256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20309009256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30715560000).

20309009256 is an abundant number, since it is smaller than the sum of its proper divisors (41122110744).

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

20309009256 is a wasteful number, since it uses less digits than its factorization.

20309009256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170704 (or 170694 counting only the distinct ones).

The product of its (nonzero) digits is 29160, while the sum is 36.

Adding to 20309009256 its reverse (65290090302), we get a palindrome (85599099558).

The spelling of 20309009256 in words is "twenty billion, three hundred nine million, nine thousand, two hundred fifty-six".