20978341920 has 144 divisors (see below), whose sum is σ = 71902335960. Its totient is φ = 5569708032.

The previous prime is 20978341919. The next prime is 20978341933. The reversal of 20978341920 is 2914387902.

20978341920 is a `hidden beast` number, since 209 + 7 + 8 + 3 + 419 + 20 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 20367856656 + 610485264 = 142716^2 + 24708^2 .

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

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 23 ways as a sum of consecutive naturals, for example, 297952 + ... + 361568.

Almost surely, 2^20978341920 is an apocalyptic number.

20978341920 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 20978341920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35951167980).

20978341920 is an abundant number, since it is smaller than the sum of its proper divisors (50923994040).

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

20978341920 is a wasteful number, since it uses less digits than its factorization.

20978341920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63867 (or 63856 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The spelling of 20978341920 in words is "twenty billion, nine hundred seventy-eight million, three hundred forty-one thousand, nine hundred twenty".