21531017088 has 288 divisors, whose sum is σ = 73161864360. Its totient is φ = 6058838016.

The previous prime is 21531017069. The next prime is 21531017093. The reversal of 21531017088 is 88071013512.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3779170 + ... + 3784862.

Almost surely, 2^21531017088 is an apocalyptic number.

21531017088 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 21531017088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36580932180).

21531017088 is an abundant number, since it is smaller than the sum of its proper divisors (51630847272).

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

21531017088 is a wasteful number, since it uses less digits than its factorization.

21531017088 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5794 (or 5772 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 36.

The spelling of 21531017088 in words is "twenty-one billion, five hundred thirty-one million, seventeen thousand, eighty-eight".