66649157 has 2 divisors, whose sum is σ = 66649158. Its totient is φ = 66649156.

The previous prime is 66649153. The next prime is 66649159. The reversal of 66649157 is 75194666.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66080641 + 568516 = 8129^2 + 754^2 .

It is a cyclic number.

It is not a de Polignac number, because 66649157 - 2² = 66649153 is a prime.

It is a super-2 number, since 2×66649157² = 8884220257621298, which contains 22 as substring.

Together with 66649159, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66649151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33324578 + 33324579.

It is an arithmetic number, because the mean of its divisors is an integer number (33324579).

Almost surely, 2^66649157 is an apocalyptic number.

It is an amenable number.

66649157 is a deficient number, since it is larger than the sum of its proper divisors (1).

66649157 is an equidigital number, since it uses as much as digits as its factorization.

66649157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 44.

The square root of 66649157 is about 8163.8934951407. The cubic root of 66649157 is about 405.4446308200. Note that the first 3 decimals are identical.

The spelling of 66649157 in words is "sixty-six million, six hundred forty-nine thousand, one hundred fifty-seven".