67009991 has 2 divisors, whose sum is σ = 67009992. Its totient is φ = 67009990.

The previous prime is 67009961. The next prime is 67010029. The reversal of 67009991 is 19990076.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 67009991 - 2¹⁰ = 67008967 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (67009931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33504995 + 33504996.

It is an arithmetic number, because the mean of its divisors is an integer number (33504996).

Almost surely, 2^67009991 is an apocalyptic number.

67009991 is a deficient number, since it is larger than the sum of its proper divisors (1).

67009991 is an equidigital number, since it uses as much as digits as its factorization.

67009991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30618, while the sum is 41.

The square root of 67009991 is about 8185.9630465816. The cubic root of 67009991 is about 406.1749975621.

The spelling of 67009991 in words is "sixty-seven million, nine thousand, nine hundred ninety-one".