20840991984 has 320 divisors, whose sum is σ = 64624435200. Its totient is φ = 6415718400.

The previous prime is 20840991979. The next prime is 20840992009. The reversal of 20840991984 is 48919904802.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 20840991984.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 40001644 + ... + 40002164.

It is an arithmetic number, because the mean of its divisors is an integer number (201951360).

Almost surely, 2^20840991984 is an apocalyptic number.

20840991984 is a gapful number since it is divisible by the number (24) 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 20840991984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32312217600).

20840991984 is an abundant number, since it is smaller than the sum of its proper divisors (43783443216).

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

20840991984 is a wasteful number, since it uses less digits than its factorization.

20840991984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701 (or 689 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 54.

The spelling of 20840991984 in words is "twenty billion, eight hundred forty million, nine hundred ninety-one thousand, nine hundred eighty-four".