661369 has 4 divisors (see below), whose sum is σ = 663796. Its totient is φ = 658944.

The previous prime is 661361. The next prime is 661373. The reversal of 661369 is 963166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2025 + 659344 = 45^2 + 812^2 .

It is a cyclic number.

It is not a de Polignac number, because 661369 - 2³ = 661361 is a prime.

It is a super-2 number, since 2×661369² = 874817908322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661369.

It is not an unprimeable number, because it can be changed into a prime (661361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 744 + ... + 1369.

It is an arithmetic number, because the mean of its divisors is an integer number (165949).

2⁶⁶¹³⁶⁹ is an apocalyptic number.

It is an amenable number.

661369 is a deficient number, since it is larger than the sum of its proper divisors (2427).

661369 is a wasteful number, since it uses less digits than its factorization.

661369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2426.

The product of its digits is 5832, while the sum is 31.

The square root of 661369 is about 813.2459652528. The cubic root of 661369 is about 87.1260339160.

The spelling of 661369 in words is "six hundred sixty-one thousand, three hundred sixty-nine".