20991087360 has 288 divisors, whose sum is σ = 76079969280. Its totient is φ = 5478100992.

The previous prime is 20991087329. The next prime is 20991087367. The reversal of 20991087360 is 6378019902.

20991087360 is a `hidden beast` number, since 209 + 9 + 1 + 0 + 87 + 360 = 666.

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 (45).

It is not an unprimeable number, because it can be changed into a prime (20991087367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1617859 + ... + 1630781.

It is an arithmetic number, because the mean of its divisors is an integer number (264166560).

Almost surely, 2^20991087360 is an apocalyptic number.

20991087360 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 20991087360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38039984640).

20991087360 is an abundant number, since it is smaller than the sum of its proper divisors (55088881920).

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

20991087360 is a wasteful number, since it uses less digits than its factorization.

20991087360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13000 (or 12980 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The spelling of 20991087360 in words is "twenty billion, nine hundred ninety-one million, eighty-seven thousand, three hundred sixty".