397616581 has 4 divisors (see below), whose sum is σ = 398287692. Its totient is φ = 396945472.

The previous prime is 397616579. The next prime is 397616599. The reversal of 397616581 is 185616793.

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: 185616793 = 9661 ⋅19213.

It can be written as a sum of positive squares in 2 ways, for example, as 324360100 + 73256481 = 18010^2 + 8559^2 .

It is a cyclic number.

It is not a de Polignac number, because 397616581 - 2¹ = 397616579 is a prime.

It is a super-2 number, since 2×397616581² = 316197890972259122, 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 (397616551) 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, 334666 + ... + 335851.

It is an arithmetic number, because the mean of its divisors is an integer number (99571923).

Almost surely, 2^397616581 is an apocalyptic number.

It is an amenable number.

397616581 is a deficient number, since it is larger than the sum of its proper divisors (671111).

397616581 is an equidigital number, since it uses as much as digits as its factorization.

397616581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 671110.

The product of its digits is 272160, while the sum is 46.

The square root of 397616581 is about 19940.3254988478. The cubic root of 397616581 is about 735.3399516468.

The spelling of 397616581 in words is "three hundred ninety-seven million, six hundred sixteen thousand, five hundred eighty-one".