21539523485 has 4 divisors (see below), whose sum is σ = 25847428188. Its totient is φ = 17231618784.

The previous prime is 21539523479. The next prime is 21539523517. The reversal of 21539523485 is 58432593512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2471780089 + 19067743396 = 49717^2 + 138086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21539523485 - 2²⁸ = 21271088029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2153952344 + ... + 2153952353.

It is an arithmetic number, because the mean of its divisors is an integer number (6461857047).

Almost surely, 2^21539523485 is an apocalyptic number.

It is an amenable number.

21539523485 is a deficient number, since it is larger than the sum of its proper divisors (4307904703).

21539523485 is an equidigital number, since it uses as much as digits as its factorization.

21539523485 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4307904702.

The product of its digits is 1296000, while the sum is 47.

The spelling of 21539523485 in words is "twenty-one billion, five hundred thirty-nine million, five hundred twenty-three thousand, four hundred eighty-five".