61686728 has 16 divisors (see below), whose sum is σ = 115897500. Its totient is φ = 30780736.

The previous prime is 61686707. The next prime is 61686731. The reversal of 61686728 is 82768616.

61686728 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 57183844 + 4502884 = 7562^2 + 2122^2 .

It is a super-2 number, since 2×61686728² = 7610504822691968, which contains 22 as substring.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 3503 + ... + 11646.

Almost surely, 2^61686728 is an apocalyptic number.

It is an amenable number.

61686728 is a deficient number, since it is larger than the sum of its proper divisors (54210772).

61686728 is a wasteful number, since it uses less digits than its factorization.

61686728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15664 (or 15660 counting only the distinct ones).

The product of its digits is 193536, while the sum is 44.

The square root of 61686728 is about 7854.0898899873. The cubic root of 61686728 is about 395.1214239744.

The spelling of 61686728 in words is "sixty-one million, six hundred eighty-six thousand, seven hundred twenty-eight".