20511409840 has 160 divisors (see below), whose sum is σ = 51173778240. Its totient is φ = 7618854912.

The previous prime is 20511409819. The next prime is 20511409843. The reversal of 20511409840 is 4890411502.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a junction number, because it is equal to n+sod(n) for n = 20511409796 and 20511409805.

It is not an unprimeable number, because it can be changed into a prime (20511409843) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52728366 + ... + 52728754.

It is an arithmetic number, because the mean of its divisors is an integer number (319836114).

Almost surely, 2^20511409840 is an apocalyptic number.

20511409840 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 20511409840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25586889120).

20511409840 is an abundant number, since it is smaller than the sum of its proper divisors (30662368400).

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

20511409840 is a wasteful number, since it uses less digits than its factorization.

20511409840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 839 (or 833 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 34.

The spelling of 20511409840 in words is "twenty billion, five hundred eleven million, four hundred nine thousand, eight hundred forty".