20801921868 has 144 divisors (see below), whose sum is σ = 66295983936. Its totient is φ = 5352376320.

The previous prime is 20801921857. The next prime is 20801921887. The reversal of 20801921868 is 86812910802.

It is a happy 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, 56880 + ... + 211752.

Almost surely, 2^20801921868 is an apocalyptic number.

20801921868 is a gapful number since it is divisible by the number (28) 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 20801921868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33147991968).

20801921868 is an abundant number, since it is smaller than the sum of its proper divisors (45494062068).

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

20801921868 is a wasteful number, since it uses less digits than its factorization.

20801921868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154944 (or 154939 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The spelling of 20801921868 in words is "twenty billion, eight hundred one million, nine hundred twenty-one thousand, eight hundred sixty-eight".