21781135488 has 256 divisors, whose sum is σ = 73698508800. Its totient is φ = 5548621824.

The previous prime is 21781135483. The next prime is 21781135489. The reversal of 21781135488 is 88453118712.

It is a super-2 number, since 2×21781135488² (a number of 21 digits) contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (21781135483) 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, 855681 + ... + 880767.

It is an arithmetic number, because the mean of its divisors is an integer number (287884800).

Almost surely, 2^21781135488 is an apocalyptic number.

21781135488 is a gapful number since it is divisible by the number (28) 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 21781135488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36849254400).

21781135488 is an abundant number, since it is smaller than the sum of its proper divisors (51917373312).

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

21781135488 is a wasteful number, since it uses less digits than its factorization.

21781135488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25147 (or 25135 counting only the distinct ones).

The product of its digits is 430080, while the sum is 48.

The spelling of 21781135488 in words is "twenty-one billion, seven hundred eighty-one million, one hundred thirty-five thousand, four hundred eighty-eight".