21135314403856 has 135 divisors (see below), whose sum is σ = 43572015836109. Its totient is φ = 9930202560000.

The previous prime is 21135314403851. The next prime is 21135314403857. The reversal of 21135314403856 is 65830441353112.

The square root of 21135314403856 is 4597316.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 15895244029456 + 5240070374400 = 3986884^2 + 2289120^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21135314403851) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 84204439731 + ... + 84204439981.

Almost surely, 2^{21135314403856} is an apocalyptic number.

21135314403856 is the 4597316-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21135314403856

21135314403856 is an abundant number, since it is smaller than the sum of its proper divisors (22436701432253).

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

21135314403856 is an frugal number, since it uses more digits than its factorization.

21135314403856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1030 (or 513 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 46.

Adding to 21135314403856 its reverse (65830441353112), we get a palindrome (86965755756968).

The spelling of 21135314403856 in words is "twenty-one trillion, one hundred thirty-five billion, three hundred fourteen million, four hundred three thousand, eight hundred fifty-six".