11651561 has 2 divisors, whose sum is σ = 11651562. Its totient is φ = 11651560.

The previous prime is 11651557. The next prime is 11651569. The reversal of 11651561 is 16515611.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11182336 + 469225 = 3344^2 + 685^2 .

It is a cyclic number.

It is not a de Polignac number, because 11651561 - 2² = 11651557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 11651561.

It is not a weakly prime, because it can be changed into another prime (11651569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5825780 + 5825781.

It is an arithmetic number, because the mean of its divisors is an integer number (5825781).

Almost surely, 2^11651561 is an apocalyptic number.

It is an amenable number.

11651561 is a deficient number, since it is larger than the sum of its proper divisors (1).

11651561 is an equidigital number, since it uses as much as digits as its factorization.

11651561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 900, while the sum is 26.

The square root of 11651561 is about 3413.4382959122. The cubic root of 11651561 is about 226.7051422095.

The spelling of 11651561 in words is "eleven million, six hundred fifty-one thousand, five hundred sixty-one".