398661 has 4 divisors (see below), whose sum is σ = 531552. Its totient is φ = 265772.

The previous prime is 398627. The next prime is 398669. The reversal of 398661 is 166893.

398661 is digitally balanced in base 7, 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, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 166893 = 3 ⋅55631.

It is a cyclic number.

It is not a de Polignac number, because 398661 - 2⁹ = 398149 is a prime.

It is an Ulam number.

It is a D-number.

398661 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398669) 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, 66441 + ... + 66446.

It is an arithmetic number, because the mean of its divisors is an integer number (132888).

2³⁹⁸⁶⁶¹ is an apocalyptic number.

It is an amenable number.

398661 is a deficient number, since it is larger than the sum of its proper divisors (132891).

398661 is a wasteful number, since it uses less digits than its factorization.

398661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132890.

The product of its digits is 7776, while the sum is 33.

The square root of 398661 is about 631.3960722082. The cubic root of 398661 is about 73.5983227603.

The spelling of 398661 in words is "three hundred ninety-eight thousand, six hundred sixty-one".