661266 has 24 divisors (see below), whose sum is σ = 1517724. Its totient is φ = 207360.

The previous prime is 661259. The next prime is 661267. The reversal of 661266 is 662166.

It can be written as a sum of positive squares in 2 ways, for example, as 632025 + 29241 = 795^2 + 171^2 .

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661267) by changing a digit.

661266 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 775 + ... + 1386.

2⁶⁶¹²⁶⁶ is an apocalyptic number.

661266 is an abundant number, since it is smaller than the sum of its proper divisors (856458).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661266 is a wasteful number, since it uses less digits than its factorization.

661266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2186 (or 2183 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 661266 is about 813.1826363124. The cubic root of 661266 is about 87.1215107490.

Subtracting 661266 from its reverse (662166), we obtain a square (900 = 30²).

The spelling of 661266 in words is "six hundred sixty-one thousand, two hundred sixty-six".