328681921 has 2 divisors, whose sum is σ = 328681922. Its totient is φ = 328681920.

The previous prime is 328681877. The next prime is 328681939. The reversal of 328681921 is 129186823.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 298045696 + 30636225 = 17264^2 + 5535^2 .

It is a cyclic number.

It is not a de Polignac number, because 328681921 - 2¹⁹ = 328157633 is a prime.

It is not a weakly prime, because it can be changed into another prime (328681321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 164340960 + 164340961.

It is an arithmetic number, because the mean of its divisors is an integer number (164340961).

Almost surely, 2^328681921 is an apocalyptic number.

It is an amenable number.

328681921 is a deficient number, since it is larger than the sum of its proper divisors (1).

328681921 is an equidigital number, since it uses as much as digits as its factorization.

328681921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 40.

The square root of 328681921 is about 18129.5868954590. The cubic root of 328681921 is about 690.1210464665.

The spelling of 328681921 in words is "three hundred twenty-eight million, six hundred eighty-one thousand, nine hundred twenty-one".