20974121856 has 160 divisors (see below), whose sum is σ = 64433138880. Its totient is φ = 6765742080.

The previous prime is 20974121821. The next prime is 20974121867. The reversal of 20974121856 is 65812147902.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 288780 + ... + 354036.

It is an arithmetic number, because the mean of its divisors is an integer number (402707118).

Almost surely, 2^20974121856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20974121856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32216569440).

20974121856 is an abundant number, since it is smaller than the sum of its proper divisors (43459017024).

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

20974121856 is an equidigital number, since it uses as much as digits as its factorization.

20974121856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65314 (or 65293 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 20974121856 in words is "twenty billion, nine hundred seventy-four million, one hundred twenty-one thousand, eight hundred fifty-six".