661319 has 4 divisors (see below), whose sum is σ = 690096. Its totient is φ = 632544.

The previous prime is 661267. The next prime is 661321. The reversal of 661319 is 913166.

661319 is digitally balanced in base 2, 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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661319 is a prime.

It is a super-2 number, since 2×661319² = 874685639522, 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 (661019) 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, 14354 + ... + 14399.

It is an arithmetic number, because the mean of its divisors is an integer number (172524).

2⁶⁶¹³¹⁹ is an apocalyptic number.

661319 is a deficient number, since it is larger than the sum of its proper divisors (28777).

661319 is a wasteful number, since it uses less digits than its factorization.

661319 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28776.

The product of its digits is 972, while the sum is 26.

The square root of 661319 is about 813.2152236647. The cubic root of 661319 is about 87.1238382625.

The spelling of 661319 in words is "six hundred sixty-one thousand, three hundred nineteen".