61287561 has 12 divisors (see below), whose sum is σ = 88874292. Its totient is φ = 40697856.

The previous prime is 61287553. The next prime is 61287563. The reversal of 61287561 is 16578216.

61287561 is a `hidden beast` number, since 6 + 12 + 87 + 561 = 666.

61287561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 58614336 + 2673225 = 7656^2 + 1635^2 .

It is not a de Polignac number, because 61287561 - 2³ = 61287553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61287563) 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 in 11 ways as a sum of consecutive naturals, for example, 10936 + ... + 15561.

It is an arithmetic number, because the mean of its divisors is an integer number (7406191).

Almost surely, 2^61287561 is an apocalyptic number.

It is an amenable number.

61287561 is a deficient number, since it is larger than the sum of its proper divisors (27586731).

61287561 is a wasteful number, since it uses less digits than its factorization.

61287561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26760 (or 26757 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 61287561 is about 7828.6372377317. The cubic root of 61287561 is about 394.2673188263.

It can be divided in two parts, 6128 and 7561, that added together give a square (13689 = 117²).

The spelling of 61287561 in words is "sixty-one million, two hundred eighty-seven thousand, five hundred sixty-one".