66545865 has 24 divisors (see below), whose sum is σ = 119325960. Its totient is φ = 34266624.

The previous prime is 66545819. The next prime is 66545893. The reversal of 66545865 is 56854566.

It is a happy number.

66545865 is a `hidden beast` number, since 6 + 65 + 4 + 586 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 9216 + 66536649 = 96^2 + 8157^2 .

It is a de Polignac number, because none of the positive numbers 2^k-66545865 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 66545865.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24192 + ... + 26801.

It is an arithmetic number, because the mean of its divisors is an integer number (4971915).

Almost surely, 2^66545865 is an apocalyptic number.

It is an amenable number.

66545865 is a deficient number, since it is larger than the sum of its proper divisors (52780095).

66545865 is a wasteful number, since it uses less digits than its factorization.

66545865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51033 (or 51030 counting only the distinct ones).

The product of its digits is 864000, while the sum is 45.

The square root of 66545865 is about 8157.5648940110. The cubic root of 66545865 is about 405.2350715801.

The spelling of 66545865 in words is "sixty-six million, five hundred forty-five thousand, eight hundred sixty-five".