66864665 has 12 divisors (see below), whose sum is σ = 93337956. Its totient is φ = 45849888.

The previous prime is 66864647. The next prime is 66864683. The reversal of 66864665 is 56646866.

It is an interprime number because it is at equal distance from previous prime (66864647) and next prime (66864683).

It can be written as a sum of positive squares in 2 ways, for example, as 25120144 + 41744521 = 5012^2 + 6461^2 .

It is a de Polignac number, because none of the positive numbers 2^k-66864665 is a prime.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 136214 + ... + 136703.

It is an arithmetic number, because the mean of its divisors is an integer number (7778163).

Almost surely, 2^66864665 is an apocalyptic number.

It is an amenable number.

66864665 is a deficient number, since it is larger than the sum of its proper divisors (26473291).

66864665 is a wasteful number, since it uses less digits than its factorization.

66864665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272936 (or 272929 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 47.

The square root of 66864665 is about 8177.0816921442. The cubic root of 66864665 is about 405.8811582410.

The spelling of 66864665 in words is "sixty-six million, eight hundred sixty-four thousand, six hundred sixty-five".