66191731 has 4 divisors (see below), whose sum is σ = 66341592. Its totient is φ = 66041872.

The previous prime is 66191729. The next prime is 66191737. The reversal of 66191731 is 13719166.

66191731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 66191731 - 2¹ = 66191729 is a prime.

It is a super-2 number, since 2×66191731² = 8762690505552722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66191737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74266 + ... + 75151.

It is an arithmetic number, because the mean of its divisors is an integer number (16585398).

Almost surely, 2^66191731 is an apocalyptic number.

66191731 is a deficient number, since it is larger than the sum of its proper divisors (149861).

66191731 is a wasteful number, since it uses less digits than its factorization.

66191731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149860.

The product of its digits is 6804, while the sum is 34.

The square root of 66191731 is about 8135.8300744300. The cubic root of 66191731 is about 404.5149525170.

The spelling of 66191731 in words is "sixty-six million, one hundred ninety-one thousand, seven hundred thirty-one".