21243524531 has 4 divisors (see below), whose sum is σ = 21274628472.
Its totient is φ = 21212420592.
The previous prime is 21243524527. The next prime is 21243524537. The reversal of 21243524531 is 13542534212.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 21243524531 - 22 = 21243524527 is a prime.
It is a super-2 number, since 2×212435245312 (a number of 21 digits) contains 22 as substring.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (21243524537) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15550946 + ... + 15552311.
It is an arithmetic number, because the mean of its divisors is an integer number (5318657118).
Almost surely, 221243524531 is an apocalyptic number.
21243524531 is a deficient number, since it is larger than the sum of its proper divisors (31103941).
21243524531 is an equidigital number, since it uses as much as digits as its factorization.
21243524531 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 31103940.
The product of its digits is 28800, while the sum is 32.
The spelling of 21243524531 in words is "twenty-one billion, two hundred forty-three million, five hundred twenty-four thousand, five hundred thirty-one".