321671921 has 2 divisors, whose sum is σ = 321671922. Its totient is φ = 321671920.

The previous prime is 321671897. The next prime is 321671923. The reversal of 321671921 is 129176123.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 314707600 + 6964321 = 17740^2 + 2639^2 .

It is an emirp because it is prime and its reverse (129176123) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-321671921 is a prime.

Together with 321671923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (321671923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160835960 + 160835961.

It is an arithmetic number, because the mean of its divisors is an integer number (160835961).

Almost surely, 2^321671921 is an apocalyptic number.

It is an amenable number.

321671921 is a deficient number, since it is larger than the sum of its proper divisors (1).

321671921 is an equidigital number, since it uses as much as digits as its factorization.

321671921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4536, while the sum is 32.

The square root of 321671921 is about 17935.2145512676. The cubic root of 321671921 is about 685.1795370056.

The spelling of 321671921 in words is "three hundred twenty-one million, six hundred seventy-one thousand, nine hundred twenty-one".