21817378752 has 224 divisors, whose sum is σ = 63278820864. Its totient is φ = 6594048000.

The previous prime is 21817378703. The next prime is 21817378753. The reversal of 21817378752 is 25787371812.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21817378695 and 21817378704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21817378753) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40327602 + ... + 40328142.

It is an arithmetic number, because the mean of its divisors is an integer number (282494736).

Almost surely, 2^21817378752 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 21817378752, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31639410432).

21817378752 is an abundant number, since it is smaller than the sum of its proper divisors (41461442112).

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

21817378752 is a wasteful number, since it uses less digits than its factorization.

21817378752 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 827 (or 817 counting only the distinct ones).

The product of its digits is 1317120, while the sum is 51.

The spelling of 21817378752 in words is "twenty-one billion, eight hundred seventeen million, three hundred seventy-eight thousand, seven hundred fifty-two".