661286 has 4 divisors (see below), whose sum is σ = 991932. Its totient is φ = 330642.

The previous prime is 661267. The next prime is 661321. The reversal of 661286 is 682166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 682166 = 2 ⋅341083.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165320 + ... + 165323.

It is an arithmetic number, because the mean of its divisors is an integer number (247983).

2⁶⁶¹²⁸⁶ is an apocalyptic number.

661286 is a deficient number, since it is larger than the sum of its proper divisors (330646).

661286 is a wasteful number, since it uses less digits than its factorization.

661286 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330645.

The product of its digits is 3456, while the sum is 29.

The square root of 661286 is about 813.1949335799. The cubic root of 661286 is about 87.1223890706.

The spelling of 661286 in words is "six hundred sixty-one thousand, two hundred eighty-six".