51661647 has 6 divisors (see below), whose sum is σ = 74622392. Its totient is φ = 34441092.

The previous prime is 51661637. The next prime is 51661651. The reversal of 51661647 is 74616615.

51661647 is a `hidden beast` number, since 5 + 1 + 6 + 6 + 1 + 647 = 666.

51661647 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 51661647 - 2⁸ = 51661391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51661637) 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 5 ways as a sum of consecutive naturals, for example, 2870083 + ... + 2870100.

Almost surely, 2^51661647 is an apocalyptic number.

51661647 is a deficient number, since it is larger than the sum of its proper divisors (22960745).

51661647 is a wasteful number, since it uses less digits than its factorization.

51661647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5740189 (or 5740186 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 51661647 is about 7187.6037035997. The cubic root of 51661647 is about 372.4397980874.

The spelling of 51661647 in words is "fifty-one million, six hundred sixty-one thousand, six hundred forty-seven".