21027975840 has 168 divisors, whose sum is σ = 74484229428. Its totient is φ = 5607429120.

The previous prime is 21027975823. The next prime is 21027975847. The reversal of 21027975840 is 4857972012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20725633296 + 302342544 = 143964^2 + 17388^2 .

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 (21027975847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 26500 + ... + 206780.

Almost surely, 2^21027975840 is an apocalyptic number.

21027975840 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 21027975840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37242114714).

21027975840 is an abundant number, since it is smaller than the sum of its proper divisors (53456253588).

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

21027975840 is an equidigital number, since it uses as much as digits as its factorization.

21027975840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180314 (or 180291 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 45.

The spelling of 21027975840 in words is "twenty-one billion, twenty-seven million, nine hundred seventy-five thousand, eight hundred forty".