328990661 has 4 divisors (see below), whose sum is σ = 329056812. Its totient is φ = 328924512.

The previous prime is 328990639. The next prime is 328990687. The reversal of 328990661 is 166099823.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166099823 = 383 ⋅433681.

It can be written as a sum of positive squares in 2 ways, for example, as 70392100 + 258598561 = 8390^2 + 16081^2 .

It is a cyclic number.

It is not a de Polignac number, because 328990661 - 2¹⁰ = 328989637 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 (328990691) 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, 24950 + ... + 35783.

It is an arithmetic number, because the mean of its divisors is an integer number (82264203).

Almost surely, 2^328990661 is an apocalyptic number.

It is an amenable number.

328990661 is a deficient number, since it is larger than the sum of its proper divisors (66151).

328990661 is an equidigital number, since it uses as much as digits as its factorization.

328990661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66150.

The product of its (nonzero) digits is 139968, while the sum is 44.

The square root of 328990661 is about 18138.0997075217. The cubic root of 328990661 is about 690.3370620929.

The spelling of 328990661 in words is "three hundred twenty-eight million, nine hundred ninety thousand, six hundred sixty-one".