321331661 has 8 divisors (see below), whose sum is σ = 374731200. Its totient is φ = 275426844.

The previous prime is 321331639. The next prime is 321331663. The reversal of 321331661 is 166133123.

It is not a de Polignac number, because 321331661 - 2¹⁰ = 321330637 is a prime.

It is a super-2 number, since 2×321331661² = 206508072722037842, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 321331661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (321331663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 468071 + ... + 468756.

It is an arithmetic number, because the mean of its divisors is an integer number (46841400).

Almost surely, 2^321331661 is an apocalyptic number.

It is an amenable number.

321331661 is a deficient number, since it is larger than the sum of its proper divisors (53399539).

321331661 is an frugal number, since it uses more digits than its factorization.

321331661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 936848 (or 936834 counting only the distinct ones).

The product of its digits is 1944, while the sum is 26.

The square root of 321331661 is about 17925.7262335449. The cubic root of 321331661 is about 684.9378607031.

Adding to 321331661 its reverse (166133123), we get a palindrome (487464784).

The spelling of 321331661 in words is "three hundred twenty-one million, three hundred thirty-one thousand, six hundred sixty-one".