21205939539456 has 1280 divisors, whose sum is σ = 78377840640000. Its totient is φ = 5523616530432.

The previous prime is 21205939539413. The next prime is 21205939539457. The reversal of 21205939539456 is 65493593950212.

It is a happy number.

21205939539456 is a `hidden beast` number, since 2 + 1 + 2 + 0 + 5 + 93 + 9 + 539 + 4 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 21205939539393 and 21205939539402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205939539457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 24686774355 + ... + 24686775213.

It is an arithmetic number, because the mean of its divisors is an integer number (61232688000).

Almost surely, 2^{21205939539456} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21205939539456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39188920320000).

21205939539456 is an abundant number, since it is smaller than the sum of its proper divisors (57171901100544).

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

21205939539456 is a wasteful number, since it uses less digits than its factorization.

21205939539456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1404 (or 1382 counting only the distinct ones).

The product of its (nonzero) digits is 78732000, while the sum is 63.

The spelling of 21205939539456 in words is "twenty-one trillion, two hundred five billion, nine hundred thirty-nine million, five hundred thirty-nine thousand, four hundred fifty-six".