66907691 has 2 divisors, whose sum is σ = 66907692. Its totient is φ = 66907690.

The previous prime is 66907657. The next prime is 66907717. The reversal of 66907691 is 19670966.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66907691 - 2⁶ = 66907627 is a prime.

It is a super-2 number, since 2×66907691² = 8953278229902962, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66907651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33453845 + 33453846.

It is an arithmetic number, because the mean of its divisors is an integer number (33453846).

Almost surely, 2^66907691 is an apocalyptic number.

66907691 is a deficient number, since it is larger than the sum of its proper divisors (1).

66907691 is an equidigital number, since it uses as much as digits as its factorization.

66907691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 122472, while the sum is 44.

The square root of 66907691 is about 8179.7121587498. The cubic root of 66907691 is about 405.9681982257.

The spelling of 66907691 in words is "sixty-six million, nine hundred seven thousand, six hundred ninety-one".