21171071724 has 96 divisors (see below), whose sum is σ = 55809734400. Its totient is φ = 6187426560.

The previous prime is 21171071711. The next prime is 21171071731. The reversal of 21171071724 is 42717017112.

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 4242759 + ... + 4247745.

It is an arithmetic number, because the mean of its divisors is an integer number (581351400).

Almost surely, 2^21171071724 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 21171071724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27904867200).

21171071724 is an abundant number, since it is smaller than the sum of its proper divisors (34638662676).

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

21171071724 is a wasteful number, since it uses less digits than its factorization.

21171071724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6143 (or 6141 counting only the distinct ones).

The product of its (nonzero) digits is 5488, while the sum is 33.

Adding to 21171071724 its reverse (42717017112), we get a palindrome (63888088836).

The spelling of 21171071724 in words is "twenty-one billion, one hundred seventy-one million, seventy-one thousand, seven hundred twenty-four".