661131 has 6 divisors (see below), whose sum is σ = 954980. Its totient is φ = 440748.

The previous prime is 661121. The next prime is 661139. The reversal of 661131 is 131166.

661131 is a `hidden beast` number, since 661 + 1 + 3 + 1 = 666.

It is not a de Polignac number, because 661131 - 2⁵ = 661099 is a prime.

It is a super-2 number, since 2×661131² = 874188398322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661139) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36721 + ... + 36738.

2⁶⁶¹¹³¹ is an apocalyptic number.

661131 is a deficient number, since it is larger than the sum of its proper divisors (293849).

661131 is a wasteful number, since it uses less digits than its factorization.

661131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73465 (or 73462 counting only the distinct ones).

The product of its digits is 108, while the sum is 18.

The square root of 661131 is about 813.0996248923. The cubic root of 661131 is about 87.1155816148.

Adding to 661131 its reverse (131166), we get a palindrome (792297).

The spelling of 661131 in words is "six hundred sixty-one thousand, one hundred thirty-one".