66156985 has 16 divisors (see below), whose sum is σ = 82872720. Its totient is φ = 50652160.

The previous prime is 66156983. The next prime is 66156989. The reversal of 66156985 is 58965166.

It can be written as a sum of positive squares in 8 ways, for example, as 9290304 + 56866681 = 3048^2 + 7541^2 .

It is not a de Polignac number, because 66156985 - 2¹ = 66156983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66156983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7821 + ... + 13909.

It is an arithmetic number, because the mean of its divisors is an integer number (5179545).

Almost surely, 2^66156985 is an apocalyptic number.

It is an amenable number.

66156985 is a deficient number, since it is larger than the sum of its proper divisors (16715735).

66156985 is a wasteful number, since it uses less digits than its factorization.

66156985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6188.

The product of its digits is 388800, while the sum is 46.

The square root of 66156985 is about 8133.6944250445. The cubic root of 66156985 is about 404.4441595020. Note that the first 3 decimals are identical.

It can be divided in two parts, 6615698 and 5, that added together give a triangular number (6615703 = T₃₆₃₇).

The spelling of 66156985 in words is "sixty-six million, one hundred fifty-six thousand, nine hundred eighty-five".