618661 has 4 divisors (see below), whose sum is σ = 631872. Its totient is φ = 605452.

The previous prime is 618643. The next prime is 618671. The reversal of 618661 is 166816.

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.

It is a cyclic number.

It is not a de Polignac number, because 618661 - 2¹³ = 610469 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 (618671) 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, 6535 + ... + 6628.

It is an arithmetic number, because the mean of its divisors is an integer number (157968).

2⁶¹⁸⁶⁶¹ is an apocalyptic number.

It is an amenable number.

618661 is a deficient number, since it is larger than the sum of its proper divisors (13211).

618661 is a wasteful number, since it uses less digits than its factorization.

618661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13210.

The product of its digits is 1728, while the sum is 28.

The square root of 618661 is about 786.5500619795. The cubic root of 618661 is about 85.2087602210.

The spelling of 618661 in words is "six hundred eighteen thousand, six hundred sixty-one".