661586 has 4 divisors (see below), whose sum is σ = 992382. Its totient is φ = 330792.

The previous prime is 661553. The next prime is 661603. The reversal of 661586 is 685166.

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

It can be written as a sum of positive squares in only one way, i.e., 591361 + 70225 = 769^2 + 265^2 .

It is an unprimeable number.

661586 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165395 + ... + 165398.

2⁶⁶¹⁵⁸⁶ is an apocalyptic number.

661586 is a deficient number, since it is larger than the sum of its proper divisors (330796).

661586 is a wasteful number, since it uses less digits than its factorization.

661586 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330795.

The product of its digits is 8640, while the sum is 32.

The square root of 661586 is about 813.3793702818. The cubic root of 661586 is about 87.1355617701.

The spelling of 661586 in words is "six hundred sixty-one thousand, five hundred eighty-six".