12565921 has 2 divisors, whose sum is σ = 12565922. Its totient is φ = 12565920.

The previous prime is 12565919. The next prime is 12565937. The reversal of 12565921 is 12956521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12496225 + 69696 = 3535^2 + 264^2 .

It is a cyclic number.

It is not a de Polignac number, because 12565921 - 2¹ = 12565919 is a prime.

Together with 12565919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (12565991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6282960 + 6282961.

It is an arithmetic number, because the mean of its divisors is an integer number (6282961).

Almost surely, 2^12565921 is an apocalyptic number.

It is an amenable number.

12565921 is a deficient number, since it is larger than the sum of its proper divisors (1).

12565921 is an equidigital number, since it uses as much as digits as its factorization.

12565921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5400, while the sum is 31.

The square root of 12565921 is about 3544.8442843093. The cubic root of 12565921 is about 232.4866975085.

The spelling of 12565921 in words is "twelve million, five hundred sixty-five thousand, nine hundred twenty-one".