21509452517 has 8 divisors (see below), whose sum is σ = 25375206912. Its totient is φ = 17841942000.

The previous prime is 21509452421. The next prime is 21509452537. The reversal of 21509452517 is 71525490512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21509452517 - 2²⁴ = 21492675301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21509452537) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49560734 + ... + 49561167.

It is an arithmetic number, because the mean of its divisors is an integer number (3171900864).

Almost surely, 2^21509452517 is an apocalyptic number.

It is an amenable number.

21509452517 is a deficient number, since it is larger than the sum of its proper divisors (3865754395).

21509452517 is an equidigital number, since it uses as much as digits as its factorization.

21509452517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99121939.

The product of its (nonzero) digits is 126000, while the sum is 41.

The spelling of 21509452517 in words is "twenty-one billion, five hundred nine million, four hundred fifty-two thousand, five hundred seventeen".