66640761 has 24 divisors (see below), whose sum is σ = 105618240. Its totient is φ = 40154400.

The previous prime is 66640759. The next prime is 66640787. The reversal of 66640761 is 16704666.

It is not a de Polignac number, because 66640761 - 2¹ = 66640759 is a prime.

It is a super-3 number, since 3×66640761³ (a number of 24 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (66640061) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16060 + ... + 19778.

It is an arithmetic number, because the mean of its divisors is an integer number (4400760).

Almost surely, 2^66640761 is an apocalyptic number.

It is an amenable number.

66640761 is a deficient number, since it is larger than the sum of its proper divisors (38977479).

66640761 is a wasteful number, since it uses less digits than its factorization.

66640761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3917 (or 3914 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 66640761 is about 8163.3792635158. The cubic root of 66640761 is about 405.4276050679.

The spelling of 66640761 in words is "sixty-six million, six hundred forty thousand, seven hundred sixty-one".