12961561 has 2 divisors, whose sum is σ = 12961562. Its totient is φ = 12961560.

The previous prime is 12961537. The next prime is 12961567. The reversal of 12961561 is 16516921.

12961561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12816400 + 145161 = 3580^2 + 381^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12961561 is a prime.

It is a Chen prime.

It is equal to p₈₄₆₉₁₃ and since 12961561 and 846913 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (12961567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6480780 + 6480781.

It is an arithmetic number, because the mean of its divisors is an integer number (6480781).

Almost surely, 2^12961561 is an apocalyptic number.

It is an amenable number.

12961561 is a deficient number, since it is larger than the sum of its proper divisors (1).

12961561 is an equidigital number, since it uses as much as digits as its factorization.

12961561 is an evil number, because the sum of its binary digits is even.

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

The square root of 12961561 is about 3600.2167990275. The cubic root of 12961561 is about 234.9014888143.

The spelling of 12961561 in words is "twelve million, nine hundred sixty-one thousand, five hundred sixty-one".