21172040736 has 576 divisors, whose sum is σ = 74264408064. Its totient is φ = 5215795200.

The previous prime is 21172040719. The next prime is 21172040789. The reversal of 21172040736 is 63704027112.

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

It is a junction number, because it is equal to n+sod(n) for n = 21172040697 and 21172040706.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 107472190 + ... + 107472386.

It is an arithmetic number, because the mean of its divisors is an integer number (128931264).

Almost surely, 2^21172040736 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 21172040736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37132204032).

21172040736 is an abundant number, since it is smaller than the sum of its proper divisors (53092367328).

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

21172040736 is a wasteful number, since it uses less digits than its factorization.

21172040736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333 (or 318 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 33.

Adding to 21172040736 its reverse (63704027112), we get a palindrome (84876067848).

The spelling of 21172040736 in words is "twenty-one billion, one hundred seventy-two million, forty thousand, seven hundred thirty-six".