21172707696 has 80 divisors (see below), whose sum is σ = 62747841024. Its totient is φ = 6026318592.

The previous prime is 21172707679. The next prime is 21172707697. The reversal of 21172707696 is 69670727112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21172707697) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31431 + ... + 208166.

Almost surely, 2^21172707696 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 21172707696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31373920512).

21172707696 is an abundant number, since it is smaller than the sum of its proper divisors (41575133328).

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

21172707696 is a wasteful number, since it uses less digits than its factorization.

21172707696 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239878 (or 239872 counting only the distinct ones).

The product of its (nonzero) digits is 444528, while the sum is 48.

The spelling of 21172707696 in words is "twenty-one billion, one hundred seventy-two million, seven hundred seven thousand, six hundred ninety-six".