66739991 has 8 divisors (see below), whose sum is σ = 69167520. Its totient is φ = 64320928.

The previous prime is 66739969. The next prime is 66740021. The reversal of 66739991 is 19993766.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66739991 - 2⁶ = 66739927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66739921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16985 + ... + 20541.

It is an arithmetic number, because the mean of its divisors is an integer number (8645940).

Almost surely, 2^66739991 is an apocalyptic number.

66739991 is a deficient number, since it is larger than the sum of its proper divisors (2427529).

66739991 is a wasteful number, since it uses less digits than its factorization.

66739991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4233.

The product of its digits is 551124, while the sum is 50.

The square root of 66739991 is about 8169.4547553677. The cubic root of 66739991 is about 405.6287363725.

The spelling of 66739991 in words is "sixty-six million, seven hundred thirty-nine thousand, nine hundred ninety-one".