66291997 has 2 divisors, whose sum is σ = 66291998. Its totient is φ = 66291996.

The previous prime is 66291989. The next prime is 66292021. The reversal of 66291997 is 79919266.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43309561 + 22982436 = 6581^2 + 4794^2 .

It is a cyclic number.

It is not a de Polignac number, because 66291997 - 2³ = 66291989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66291997.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66291977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33145998 + 33145999.

It is an arithmetic number, because the mean of its divisors is an integer number (33145999).

Almost surely, 2^66291997 is an apocalyptic number.

It is an amenable number.

66291997 is a deficient number, since it is larger than the sum of its proper divisors (1).

66291997 is an equidigital number, since it uses as much as digits as its factorization.

66291997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 367416, while the sum is 49.

The square root of 66291997 is about 8141.9897445281. The cubic root of 66291997 is about 404.7191000414.

The spelling of 66291997 in words is "sixty-six million, two hundred ninety-one thousand, nine hundred ninety-seven".