66557131 has 2 divisors, whose sum is σ = 66557132. Its totient is φ = 66557130.

The previous prime is 66557129. The next prime is 66557143. The reversal of 66557131 is 13175566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66557131 - 2¹ = 66557129 is a prime.

It is a super-2 number, since 2×66557131² = 8859703373902322, which contains 22 as substring.

Together with 66557129, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66557831) 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, 33278565 + 33278566.

It is an arithmetic number, because the mean of its divisors is an integer number (33278566).

Almost surely, 2^66557131 is an apocalyptic number.

66557131 is a deficient number, since it is larger than the sum of its proper divisors (1).

66557131 is an equidigital number, since it uses as much as digits as its factorization.

66557131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18900, while the sum is 34.

The square root of 66557131 is about 8158.2553894813. The cubic root of 66557131 is about 405.2579386192.

The spelling of 66557131 in words is "sixty-six million, five hundred fifty-seven thousand, one hundred thirty-one".