21521345445 has 24 divisors (see below), whose sum is σ = 38311875576. Its totient is φ = 11167832448.

The previous prime is 21521345407. The next prime is 21521345471. The reversal of 21521345445 is 54454312512.

21521345445 is a `hidden beast` number, since 2 + 152 + 13 + 454 + 45 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 873379809 + 20647965636 = 29553^2 + 143694^2 .

It is not a de Polignac number, because 21521345445 - 2¹¹ = 21521343397 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6461202 + ... + 6464531.

It is an arithmetic number, because the mean of its divisors is an integer number (1596328149).

Almost surely, 2^21521345445 is an apocalyptic number.

It is an amenable number.

21521345445 is a deficient number, since it is larger than the sum of its proper divisors (16790530131).

21521345445 is a wasteful number, since it uses less digits than its factorization.

21521345445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12925781 (or 12925778 counting only the distinct ones).

The product of its digits is 96000, while the sum is 36.

Adding to 21521345445 its reverse (54454312512), we get a palindrome (75975657957).

The spelling of 21521345445 in words is "twenty-one billion, five hundred twenty-one million, three hundred forty-five thousand, four hundred forty-five".