21216211615544 has 48 divisors (see below), whose sum is σ = 44158486637160. Its totient is φ = 9548250008000.

The previous prime is 21216211615493. The next prime is 21216211615559. The reversal of 21216211615544 is 44551611261212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 108405074 + ... + 108600609.

Almost surely, 2^{21216211615544} is an apocalyptic number.

It is an amenable number.

21216211615544 is an abundant number, since it is smaller than the sum of its proper divisors (22942275021616).

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

21216211615544 is a wasteful number, since it uses less digits than its factorization.

21216211615544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217005812 (or 217005797 counting only the distinct ones).

The product of its digits is 115200, while the sum is 41.

Adding to 21216211615544 its reverse (44551611261212), we get a palindrome (65767822876756).

The spelling of 21216211615544 in words is "twenty-one trillion, two hundred sixteen billion, two hundred eleven million, six hundred fifteen thousand, five hundred forty-four".