21352321521 has 32 divisors (see below), whose sum is σ = 34648819200. Its totient is φ = 12935543040.

The previous prime is 21352321499. The next prime is 21352321537. The reversal of 21352321521 is 12512325312.

21352321521 is a `hidden beast` number, since 2 + 135 + 2 + 3 + 2 + 1 + 521 = 666.

It is not a de Polignac number, because 21352321521 - 2¹¹ = 21352319473 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21352321541) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 788745 + ... + 815366.

It is an arithmetic number, because the mean of its divisors is an integer number (1082775600).

Almost surely, 2^21352321521 is an apocalyptic number.

It is an amenable number.

21352321521 is a deficient number, since it is larger than the sum of its proper divisors (13296497679).

21352321521 is a wasteful number, since it uses less digits than its factorization.

21352321521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1604166 (or 1604160 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

Adding to 21352321521 its reverse (12512325312), we get a palindrome (33864646833).

The spelling of 21352321521 in words is "twenty-one billion, three hundred fifty-two million, three hundred twenty-one thousand, five hundred twenty-one".