661031 has 4 divisors (see below), whose sum is σ = 755472. Its totient is φ = 566592.

The previous prime is 661027. The next prime is 661049. The reversal of 661031 is 130166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661031 - 2² = 661027 is a prime.

It is a super-2 number, since 2×661031² = 873923965922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47210 + ... + 47223.

It is an arithmetic number, because the mean of its divisors is an integer number (188868).

2⁶⁶¹⁰³¹ is an apocalyptic number.

661031 is a deficient number, since it is larger than the sum of its proper divisors (94441).

661031 is an equidigital number, since it uses as much as digits as its factorization.

661031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94440.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 661031 is about 813.0381294872. The cubic root of 661031 is about 87.1111891432. Note that the first 4 decimals are identical.

Adding to 661031 its reverse (130166), we get a palindrome (791197).

The spelling of 661031 in words is "six hundred sixty-one thousand, thirty-one".