51720666 has 8 divisors (see below), whose sum is σ = 103441344. Its totient is φ = 17240220.

The previous prime is 51720637. The next prime is 51720673. The reversal of 51720666 is 66602715.

51720666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

51720666 is an admirable number.

It is a Curzon number.

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, 4310050 + ... + 4310061.

It is an arithmetic number, because the mean of its divisors is an integer number (12930168).

Almost surely, 2^51720666 is an apocalyptic number.

51720666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51720666 is a wasteful number, since it uses less digits than its factorization.

51720666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8620116.

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 51720666 is about 7191.7081420202. The cubic root of 51720666 is about 372.5815709534.

The spelling of 51720666 in words is "fifty-one million, seven hundred twenty thousand, six hundred sixty-six".