66557751 has 16 divisors (see below), whose sum is σ = 96275424. Its totient is φ = 40656384.

The previous prime is 66557717. The next prime is 66557759. The reversal of 66557751 is 15775566.

It is not a de Polignac number, because 66557751 - 2¹⁰ = 66556727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66557759) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 886 + ... + 11571.

It is an arithmetic number, because the mean of its divisors is an integer number (6017214).

Almost surely, 2^66557751 is an apocalyptic number.

66557751 is a deficient number, since it is larger than the sum of its proper divisors (29717673).

66557751 is a wasteful number, since it uses less digits than its factorization.

66557751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12610.

The product of its digits is 220500, while the sum is 42.

The square root of 66557751 is about 8158.2933877129. The cubic root of 66557751 is about 405.2591969825.

It can be divided in two parts, 6655775 and 1, that added together give a triangular number (6655776 = T₃₆₄₈).

The spelling of 66557751 in words is "sixty-six million, five hundred fifty-seven thousand, seven hundred fifty-one".