21520530213345 has 12 divisors (see below), whose sum is σ = 37302252369876. Its totient is φ = 11477616113760.

The previous prime is 21520530213323. The next prime is 21520530213397. The reversal of 21520530213345 is 54331203502512.

21520530213345 is a `hidden beast` number, since 2 + 1 + 5 + 2 + 0 + 5 + 302 + 1 + 3 + 345 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 10022998791744 + 11497531421601 = 3165912^2 + 3390801^2 .

It is not a de Polignac number, because 21520530213345 - 2⁸ = 21520530213089 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 239117002326 + ... + 239117002415.

It is an arithmetic number, because the mean of its divisors is an integer number (3108521030823).

Almost surely, 2^{21520530213345} is an apocalyptic number.

It is an amenable number.

21520530213345 is a deficient number, since it is larger than the sum of its proper divisors (15781722156531).

21520530213345 is a wasteful number, since it uses less digits than its factorization.

21520530213345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478234004752 (or 478234004749 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 36.

Adding to 21520530213345 its reverse (54331203502512), we get a palindrome (75851733715857).

The spelling of 21520530213345 in words is "twenty-one trillion, five hundred twenty billion, five hundred thirty million, two hundred thirteen thousand, three hundred forty-five".