66831397 has 4 divisors (see below), whose sum is σ = 67493196. Its totient is φ = 66169600.

The previous prime is 66831389. The next prime is 66831407. The reversal of 66831397 is 79313866.

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 36954241 + 29877156 = 6079^2 + 5466^2 .

It is a cyclic number.

It is not a de Polignac number, because 66831397 - 2³ = 66831389 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 (66835397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 330748 + ... + 330949.

It is an arithmetic number, because the mean of its divisors is an integer number (16873299).

Almost surely, 2^66831397 is an apocalyptic number.

It is an amenable number.

66831397 is a deficient number, since it is larger than the sum of its proper divisors (661799).

66831397 is a wasteful number, since it uses less digits than its factorization.

66831397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661798.

The product of its digits is 163296, while the sum is 43.

The square root of 66831397 is about 8175.0472169890. The cubic root of 66831397 is about 405.8138327240.

The spelling of 66831397 in words is "sixty-six million, eight hundred thirty-one thousand, three hundred ninety-seven".