21236981760 has 560 divisors, whose sum is σ = 78643511496. Its totient is φ = 5478285312.

The previous prime is 21236981747. The next prime is 21236981809. The reversal of 21236981760 is 6718963212.

21236981760 is a `hidden beast` number, since 212 + 369 + 8 + 1 + 76 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 21236649984 + 331776 = 145728^2 + 576^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 122757034 + ... + 122757206.

Almost surely, 2^21236981760 is an apocalyptic number.

21236981760 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 21236981760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39321755748).

21236981760 is an abundant number, since it is smaller than the sum of its proper divisors (57406529736).

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

21236981760 is an equidigital number, since it uses as much as digits as its factorization.

21236981760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253 (or 220 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The spelling of 21236981760 in words is "twenty-one billion, two hundred thirty-six million, nine hundred eighty-one thousand, seven hundred sixty".