66209251 has 2 divisors, whose sum is σ = 66209252. Its totient is φ = 66209250.

The previous prime is 66209197. The next prime is 66209261. The reversal of 66209251 is 15290266.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66209251 - 2⁹ = 66208739 is a prime.

It is not a weakly prime, because it can be changed into another prime (66209261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33104625 + 33104626.

It is an arithmetic number, because the mean of its divisors is an integer number (33104626).

Almost surely, 2^66209251 is an apocalyptic number.

66209251 is a deficient number, since it is larger than the sum of its proper divisors (1).

66209251 is an equidigital number, since it uses as much as digits as its factorization.

66209251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 66209251 is about 8136.9067218446. The cubic root of 66209251 is about 404.5506391335.

The spelling of 66209251 in words is "sixty-six million, two hundred nine thousand, two hundred fifty-one".