12691561 has 8 divisors (see below), whose sum is σ = 13426560. Its totient is φ = 11971872.

The previous prime is 12691541. The next prime is 12691583. The reversal of 12691561 is 16519621.

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 12691561 - 2⁵ = 12691529 is a prime.

It is a super-2 number, since 2×12691561² = 322151441233442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12691501) 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, 2101 + ... + 5458.

It is an arithmetic number, because the mean of its divisors is an integer number (1678320).

Almost surely, 2^12691561 is an apocalyptic number.

It is an amenable number.

12691561 is a deficient number, since it is larger than the sum of its proper divisors (734999).

12691561 is an equidigital number, since it uses as much as digits as its factorization.

12691561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7655.

The product of its digits is 3240, while the sum is 31.

The square root of 12691561 is about 3562.5217192320. The cubic root of 12691561 is about 233.2589665502.

It can be divided in two parts, 12691 and 561, that multiplied together give a triangular number (7119651 = T₃₇₇₃).

The spelling of 12691561 in words is "twelve million, six hundred ninety-one thousand, five hundred sixty-one".