20906721966 has 96 divisors (see below), whose sum is σ = 47114846208. Its totient is φ = 6175128960.

The previous prime is 20906721929. The next prime is 20906721971. The reversal of 20906721966 is 66912760902.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3989500 + ... + 3994736.

It is an arithmetic number, because the mean of its divisors is an integer number (490779648).

Almost surely, 2^20906721966 is an apocalyptic number.

20906721966 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 20906721966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23557423104).

20906721966 is an abundant number, since it is smaller than the sum of its proper divisors (26208124242).

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

20906721966 is a wasteful number, since it uses less digits than its factorization.

20906721966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5426 (or 5413 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 48.

The spelling of 20906721966 in words is "twenty billion, nine hundred six million, seven hundred twenty-one thousand, nine hundred sixty-six".