21707771904 has 520 divisors, whose sum is σ = 79923191040. Its totient is φ = 5717164032.

The previous prime is 21707771873. The next prime is 21707771923. The reversal of 21707771904 is 40917770712.

It is a super-2 number, since 2×21707771904² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21707771904.

It is a congruent number.

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 39 ways as a sum of consecutive naturals, for example, 30191257 + ... + 30191975.

Almost surely, 2^21707771904 is an apocalyptic number.

21707771904 is a gapful number since it is divisible by the number (24) 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 21707771904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39961595520).

21707771904 is an abundant number, since it is smaller than the sum of its proper divisors (58215419136).

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

21707771904 is an equidigital number, since it uses as much as digits as its factorization.

21707771904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775 (or 744 counting only the distinct ones).

The product of its (nonzero) digits is 172872, while the sum is 45.

The spelling of 21707771904 in words is "twenty-one billion, seven hundred seven million, seven hundred seventy-one thousand, nine hundred four".