397686181 has 4 divisors (see below), whose sum is σ = 400219372. Its totient is φ = 395152992.

The previous prime is 397686167. The next prime is 397686217. The reversal of 397686181 is 181686793.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 181686793 = 277 ⋅655909.

It can be written as a sum of positive squares in 2 ways, for example, as 74909025 + 322777156 = 8655^2 + 17966^2 .

It is a cyclic number.

It is not a de Polignac number, because 397686181 - 2¹³ = 397677989 is a prime.

It is a super-2 number, since 2×397686181² = 316308597116729522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (397686161) 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, 1266360 + ... + 1266673.

It is an arithmetic number, because the mean of its divisors is an integer number (100054843).

Almost surely, 2^397686181 is an apocalyptic number.

It is an amenable number.

397686181 is a deficient number, since it is larger than the sum of its proper divisors (2533191).

397686181 is a wasteful number, since it uses less digits than its factorization.

397686181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2533190.

The product of its digits is 435456, while the sum is 49.

The square root of 397686181 is about 19942.0706297014. The cubic root of 397686181 is about 735.3828545145.

The spelling of 397686181 in words is "three hundred ninety-seven million, six hundred eighty-six thousand, one hundred eighty-one".