21779856120 has 128 divisors (see below), whose sum is σ = 73206167040. Its totient is φ = 5137251840.

The previous prime is 21779856113. The next prime is 21779856121. The reversal of 21779856120 is 2165897712.

It is a self number, because there is not a number n which added to its sum of digits gives 21779856120.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21779856121) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 174132 + ... + 271811.

It is an arithmetic number, because the mean of its divisors is an integer number (571923180).

Almost surely, 2^21779856120 is an apocalyptic number.

21779856120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21779856120 is an abundant number, since it is smaller than the sum of its proper divisors (51426310920).

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

21779856120 is a wasteful number, since it uses less digits than its factorization.

21779856120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 446005 (or 446001 counting only the distinct ones).

The product of its (nonzero) digits is 423360, while the sum is 48.

The spelling of 21779856120 in words is "twenty-one billion, seven hundred seventy-nine million, eight hundred fifty-six thousand, one hundred twenty".