1231661 has 8 divisors (see below), whose sum is σ = 1292544. Its totient is φ = 1172160.

The previous prime is 1231631. The next prime is 1231663. The reversal of 1231661 is 1661321.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1231661 - 2⁶ = 1231597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1781 + ... + 2373.

It is an arithmetic number, because the mean of its divisors is an integer number (161568).

2^1231661 is an apocalyptic number.

It is an amenable number.

1231661 is a deficient number, since it is larger than the sum of its proper divisors (60883).

1231661 is an equidigital number, since it uses as much as digits as its factorization.

1231661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691.

The product of its digits is 216, while the sum is 20.

The square root of 1231661 is about 1109.8022346346. The cubic root of 1231661 is about 107.1923346509.

Adding to 1231661 its reverse (1661321), we get a palindrome (2892982).

The spelling of 1231661 in words is "one million, two hundred thirty-one thousand, six hundred sixty-one".