21685726320 has 160 divisors (see below), whose sum is σ = 71277366528. Its totient is φ = 5435265024.

The previous prime is 21685726277. The next prime is 21685726339. The reversal of 21685726320 is 2362758612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3370947 + ... + 3377373.

Almost surely, 2^21685726320 is an apocalyptic number.

21685726320 is a gapful number since it is divisible by the number (20) 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 21685726320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35638683264).

21685726320 is an abundant number, since it is smaller than the sum of its proper divisors (49591640208).

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

21685726320 is a wasteful number, since it uses less digits than its factorization.

21685726320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7287 (or 7281 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The spelling of 21685726320 in words is "twenty-one billion, six hundred eighty-five million, seven hundred twenty-six thousand, three hundred twenty".