661330 has 16 divisors (see below), whose sum is σ = 1220184. Its totient is φ = 257920.

The previous prime is 661327. The next prime is 661343. The reversal of 661330 is 33166.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 398161 + 263169 = 631^2 + 513^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661298 and 661307.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 397 + ... + 1216.

2⁶⁶¹³³⁰ is an apocalyptic number.

661330 is a deficient number, since it is larger than the sum of its proper divisors (558854).

661330 is a wasteful number, since it uses less digits than its factorization.

661330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1661.

The product of its (nonzero) digits is 324, while the sum is 19.

The square root of 661330 is about 813.2219869138. The cubic root of 661330 is about 87.1243213158.

Adding to 661330 its reverse (33166), we get a palindrome (694496).

It can be divided in two parts, 661 and 330, that multiplied together give a triangular number (218130 = T₆₆₀).

The spelling of 661330 in words is "six hundred sixty-one thousand, three hundred thirty".