51661605 has 8 divisors (see below), whose sum is σ = 82658592. Its totient is φ = 27552848.

The previous prime is 51661537. The next prime is 51661609. The reversal of 51661605 is 50616615.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51661605 - 2⁸ = 51661349 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51661609) 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 7 ways as a sum of consecutive naturals, for example, 1722039 + ... + 1722068.

It is an arithmetic number, because the mean of its divisors is an integer number (10332324).

Almost surely, 2^51661605 is an apocalyptic number.

It is an amenable number.

51661605 is a deficient number, since it is larger than the sum of its proper divisors (30996987).

51661605 is a wasteful number, since it uses less digits than its factorization.

51661605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3444115.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 51661605 is about 7187.6007819021. The cubic root of 51661605 is about 372.4396971584.

The spelling of 51661605 in words is "fifty-one million, six hundred sixty-one thousand, six hundred five".