66905865 has 64 divisors (see below), whose sum is σ = 130233600. Its totient is φ = 32389632.

The previous prime is 66905851. The next prime is 66905869. The reversal of 66905865 is 56850966.

66905865 is a `hidden beast` number, since 6 + 69 + 0 + 586 + 5 = 666.

It is not a de Polignac number, because 66905865 - 2⁴ = 66905849 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 66905865.

It is not an unprimeable number, because it can be changed into a prime (66905869) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 117301 + ... + 117869.

It is an arithmetic number, because the mean of its divisors is an integer number (2034900).

Almost surely, 2^66905865 is an apocalyptic number.

66905865 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66905865 is a deficient number, since it is larger than the sum of its proper divisors (63327735).

66905865 is a wasteful number, since it uses less digits than its factorization.

66905865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 663 (or 657 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 45.

The square root of 66905865 is about 8179.6005403687. The cubic root of 66905865 is about 405.9645050545.

The spelling of 66905865 in words is "sixty-six million, nine hundred five thousand, eight hundred sixty-five".