1661331 has 8 divisors (see below), whose sum is σ = 2531584. Its totient is φ = 949320.

The previous prime is 1661327. The next prime is 1661333. The reversal of 1661331 is 1331661.

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

It is not a de Polignac number, because 1661331 - 2² = 1661327 is a prime.

It is a super-2 number, since 2×1661331² = 5520041383122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 79111 = 1661331 / (1 + 6 + 6 + 1 + 3 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1661298 and 1661307.

It is not an unprimeable number, because it can be changed into a prime (1661333) 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, 39535 + ... + 39576.

It is an arithmetic number, because the mean of its divisors is an integer number (316448).

2^1661331 is an apocalyptic number.

1661331 is a deficient number, since it is larger than the sum of its proper divisors (870253).

1661331 is an equidigital number, since it uses as much as digits as its factorization.

1661331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79121.

The product of its digits is 324, while the sum is 21.

The square root of 1661331 is about 1288.9262973499. The cubic root of 1661331 is about 118.4364522455.

Adding to 1661331 its reverse (1331661), we get a palindrome (2992992).

The spelling of 1661331 in words is "one million, six hundred sixty-one thousand, three hundred thirty-one".