66091957 has 4 divisors (see below), whose sum is σ = 68371020. Its totient is φ = 63812896.

The previous prime is 66091931. The next prime is 66091967. The reversal of 66091957 is 75919066.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40780996 + 25310961 = 6386^2 + 5031^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66091957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66091967) 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 in 3 ways as a sum of consecutive naturals, for example, 1139488 + ... + 1139545.

It is an arithmetic number, because the mean of its divisors is an integer number (17092755).

Almost surely, 2^66091957 is an apocalyptic number.

It is an amenable number.

66091957 is a deficient number, since it is larger than the sum of its proper divisors (2279063).

66091957 is a wasteful number, since it uses less digits than its factorization.

66091957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2279062.

The product of its (nonzero) digits is 102060, while the sum is 43.

The square root of 66091957 is about 8129.6959967763. The cubic root of 66091957 is about 404.3116019868.

The spelling of 66091957 in words is "sixty-six million, ninety-one thousand, nine hundred fifty-seven".