20644406240 has 96 divisors (see below), whose sum is σ = 50962395456. Its totient is φ = 7887953920.

The previous prime is 20644406239. The next prime is 20644406257. The reversal of 20644406240 is 4260444602.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 20644406197 and 20644406206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3017864 + ... + 3024696.

It is an arithmetic number, because the mean of its divisors is an integer number (530858286).

Almost surely, 2^20644406240 is an apocalyptic number.

20644406240 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 20644406240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25481197728).

20644406240 is an abundant number, since it is smaller than the sum of its proper divisors (30317989216).

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

20644406240 is a wasteful number, since it uses less digits than its factorization.

20644406240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7692 (or 7684 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 32.

The spelling of 20644406240 in words is "twenty billion, six hundred forty-four million, four hundred six thousand, two hundred forty".