661312 has 14 divisors (see below), whose sum is σ = 1312418. Its totient is φ = 330624.

The previous prime is 661267. The next prime is 661321. The reversal of 661312 is 213166.

It can be written as a sum of positive squares in only one way, i.e., 614656 + 46656 = 784^2 + 216^2 .

It is a super-2 number, since 2×661312² = 874667122688, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661312.

It is a congruent number.

It is an unprimeable number.

661312 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, 5103 + ... + 5230.

2⁶⁶¹³¹² is an apocalyptic number.

It is an amenable number.

661312 is a deficient number, since it is larger than the sum of its proper divisors (651106).

661312 is a wasteful number, since it uses less digits than its factorization.

661312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10345 (or 10335 counting only the distinct ones).

The product of its digits is 216, while the sum is 19.

The square root of 661312 is about 813.2109197496. The cubic root of 661312 is about 87.1235308622.

Adding to 661312 its reverse (213166), we get a palindrome (874478).

It can be divided in two parts, 66 and 1312, that added together give a triangular number (1378 = T₅₂).

The spelling of 661312 in words is "six hundred sixty-one thousand, three hundred twelve".