66631979 has 2 divisors, whose sum is σ = 66631980. Its totient is φ = 66631978.

The previous prime is 66631963. The next prime is 66631987. The reversal of 66631979 is 97913666.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66631979 - 2⁴ = 66631963 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (66631909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33315989 + 33315990.

It is an arithmetic number, because the mean of its divisors is an integer number (33315990).

Almost surely, 2^66631979 is an apocalyptic number.

66631979 is a deficient number, since it is larger than the sum of its proper divisors (1).

66631979 is an equidigital number, since it uses as much as digits as its factorization.

66631979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 367416, while the sum is 47.

The square root of 66631979 is about 8162.8413558025. The cubic root of 66631979 is about 405.4097950390.

The spelling of 66631979 in words is "sixty-six million, six hundred thirty-one thousand, nine hundred seventy-nine".