21968091684 has 144 divisors (see below), whose sum is σ = 69947369856. Its totient is φ = 5647104000.

The previous prime is 21968091623. The next prime is 21968091703. The reversal of 21968091684 is 48619086912.

It is a self number, because there is not a number n which added to its sum of digits gives 21968091684.

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, 228034 + ... + 309734.

It is an arithmetic number, because the mean of its divisors is an integer number (485745624).

Almost surely, 2^21968091684 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 21968091684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34973684928).

21968091684 is an abundant number, since it is smaller than the sum of its proper divisors (47979278172).

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

21968091684 is a wasteful number, since it uses less digits than its factorization.

21968091684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81826 (or 81821 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 54.

It can be divided in two parts, 219680 and 91684, that added together give a square (311364 = 558²).

The spelling of 21968091684 in words is "twenty-one billion, nine hundred sixty-eight million, ninety-one thousand, six hundred eighty-four".