20105408640 has 128 divisors (see below), whose sum is σ = 64142593920. Its totient is φ = 5356707840.

The previous prime is 20105408567. The next prime is 20105408663. The reversal of 20105408640 is 4680450102.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20105408598 and 20105408607.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2532357 + ... + 2540283.

It is an arithmetic number, because the mean of its divisors is an integer number (501114015).

Almost surely, 2^20105408640 is an apocalyptic number.

20105408640 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 20105408640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32071296960).

20105408640 is an abundant number, since it is smaller than the sum of its proper divisors (44037185280).

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

20105408640 is a wasteful number, since it uses less digits than its factorization.

20105408640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9270 (or 9258 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

Adding to 20105408640 its reverse (4680450102), we get a palindrome (24785858742).

The spelling of 20105408640 in words is "twenty billion, one hundred five million, four hundred eight thousand, six hundred forty".