66877991 has 2 divisors, whose sum is σ = 66877992. Its totient is φ = 66877990.

The previous prime is 66877969. The next prime is 66877999. The reversal of 66877991 is 19977866.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66877991 - 2¹⁰ = 66876967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66877999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33438995 + 33438996.

It is an arithmetic number, because the mean of its divisors is an integer number (33438996).

Almost surely, 2^66877991 is an apocalyptic number.

66877991 is a deficient number, since it is larger than the sum of its proper divisors (1).

66877991 is an equidigital number, since it uses as much as digits as its factorization.

66877991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 53.

The square root of 66877991 is about 8177.8964899294. The cubic root of 66877991 is about 405.9081202297.

The spelling of 66877991 in words is "sixty-six million, eight hundred seventy-seven thousand, nine hundred ninety-one".