21081533760 has 672 divisors, whose sum is σ = 86786069760. Its totient is φ = 4595318784.

The previous prime is 21081533741. The next prime is 21081533773. The reversal of 21081533760 is 6733518012.

It is a tau number, because it is divible by the number of its divisors (672).

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 95 ways as a sum of consecutive naturals, for example, 62556312 + ... + 62556648.

Almost surely, 2^21081533760 is an apocalyptic number.

21081533760 is a gapful number since it is divisible by the number (20) 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 21081533760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43393034880).

21081533760 is an abundant number, since it is smaller than the sum of its proper divisors (65704536000).

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

21081533760 is a wasteful number, since it uses less digits than its factorization.

21081533760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503 (or 490 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The spelling of 21081533760 in words is "twenty-one billion, eighty-one million, five hundred thirty-three thousand, seven hundred sixty".