12705521 has 4 divisors (see below), whose sum is σ = 12884544. Its totient is φ = 12526500.

The previous prime is 12705503. The next prime is 12705523. The reversal of 12705521 is 12550721.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12550721 = 181 ⋅69341.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12705521 is a prime.

It is a super-2 number, since 2×12705521² = 322860527762882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12705523) 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, 89405 + ... + 89546.

It is an arithmetic number, because the mean of its divisors is an integer number (3221136).

Almost surely, 2^12705521 is an apocalyptic number.

It is an amenable number.

12705521 is a deficient number, since it is larger than the sum of its proper divisors (179023).

12705521 is an equidigital number, since it uses as much as digits as its factorization.

12705521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179022.

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 12705521 is about 3564.4804670527. The cubic root of 12705521 is about 233.3444591067.

The spelling of 12705521 in words is "twelve million, seven hundred five thousand, five hundred twenty-one".