51663561 has 16 divisors (see below), whose sum is σ = 73297728. Its totient is φ = 32256000.

The previous prime is 51663553. The next prime is 51663607. The reversal of 51663561 is 16536615.

It is not a de Polignac number, because 51663561 - 2³ = 51663553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51663541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8361 + ... + 13161.

It is an arithmetic number, because the mean of its divisors is an integer number (4581108).

Almost surely, 2^51663561 is an apocalyptic number.

51663561 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

51663561 is a deficient number, since it is larger than the sum of its proper divisors (21634167).

51663561 is a wasteful number, since it uses less digits than its factorization.

51663561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5032.

The product of its digits is 16200, while the sum is 33.

The square root of 51663561 is about 7187.7368482715. The cubic root of 51663561 is about 372.4443975083. Note that the first 3 decimals are identical.

The spelling of 51663561 in words is "fifty-one million, six hundred sixty-three thousand, five hundred sixty-one".