21528681513 has 32 divisors (see below), whose sum is σ = 31203809280. Its totient is φ = 13166482560.

The previous prime is 21528681497. The next prime is 21528681523. The reversal of 21528681513 is 31518682512.

It is not a de Polignac number, because 21528681513 - 2⁴ = 21528681497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21528681523) 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, 102420 + ... + 231402.

It is an arithmetic number, because the mean of its divisors is an integer number (975119040).

Almost surely, 2^21528681513 is an apocalyptic number.

21528681513 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21528681513 is a deficient number, since it is larger than the sum of its proper divisors (9675127767).

21528681513 is a wasteful number, since it uses less digits than its factorization.

21528681513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129109.

The product of its digits is 115200, while the sum is 42.

Subtracting 21528681513 from its reverse (31518682512), we obtain a palindrome (9990000999).

The spelling of 21528681513 in words is "twenty-one billion, five hundred twenty-eight million, six hundred eighty-one thousand, five hundred thirteen".