397731091 has 4 divisors (see below), whose sum is σ = 401448312. Its totient is φ = 394013872.

The previous prime is 397731079. The next prime is 397731149. The reversal of 397731091 is 190137793.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190137793 = 61 ⋅3117013.

It is a cyclic number.

It is not a de Polignac number, because 397731091 - 2⁹ = 397730579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (397731011) 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, 1858450 + ... + 1858663.

It is an arithmetic number, because the mean of its divisors is an integer number (100362078).

Almost surely, 2^397731091 is an apocalyptic number.

397731091 is a deficient number, since it is larger than the sum of its proper divisors (3717221).

397731091 is a wasteful number, since it uses less digits than its factorization.

397731091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3717220.

The product of its (nonzero) digits is 35721, while the sum is 40.

The square root of 397731091 is about 19943.1966093703. The cubic root of 397731091 is about 735.4105353028.

The spelling of 397731091 in words is "three hundred ninety-seven million, seven hundred thirty-one thousand, ninety-one".