21368543940 has 108 divisors (see below), whose sum is σ = 65720946564. Its totient is φ = 5619967488.

The previous prime is 21368543923. The next prime is 21368543953. The reversal of 21368543940 is 4934586312.

21368543940 is a `hidden beast` number, since 2 + 1 + 3 + 68 + 543 + 9 + 40 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 687803076 + 20680740864 = 26226^2 + 143808^2 .

It is a super-2 number, since 2×21368543940² (a number of 21 digits) contains 22 as substring.

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

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 948082 + ... + 970358.

It is an arithmetic number, because the mean of its divisors is an integer number (608527283).

Almost surely, 2^21368543940 is an apocalyptic number.

21368543940 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 21368543940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32860473282).

21368543940 is an abundant number, since it is smaller than the sum of its proper divisors (44352402624).

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

21368543940 is a wasteful number, since it uses less digits than its factorization.

21368543940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22438 (or 22360 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 21368543940 in words is "twenty-one billion, three hundred sixty-eight million, five hundred forty-three thousand, nine hundred forty".