66998257 has 4 divisors (see below), whose sum is σ = 68556400. Its totient is φ = 65440116.

The previous prime is 66998251. The next prime is 66998273. The reversal of 66998257 is 75289966.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75289966 = 2 ⋅37644983.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66998257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66998251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 779007 + ... + 779092.

It is an arithmetic number, because the mean of its divisors is an integer number (17139100).

Almost surely, 2^66998257 is an apocalyptic number.

It is an amenable number.

66998257 is a deficient number, since it is larger than the sum of its proper divisors (1558143).

66998257 is a wasteful number, since it uses less digits than its factorization.

66998257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1558142.

The product of its digits is 1632960, while the sum is 52.

The square root of 66998257 is about 8185.2463005092. The cubic root of 66998257 is about 406.1512879850.

The spelling of 66998257 in words is "sixty-six million, nine hundred ninety-eight thousand, two hundred fifty-seven".