671921 has 2 divisors, whose sum is σ = 671922. Its totient is φ = 671920.

The previous prime is 671917. The next prime is 671933. The reversal of 671921 is 129176.

671921 is nontrivially palindromic in base 7.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 616225 + 55696 = 785^2 + 236^2 .

It is a cyclic number.

It is not a de Polignac number, because 671921 - 2² = 671917 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (671911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335960 + 335961.

It is an arithmetic number, because the mean of its divisors is an integer number (335961).

2⁶⁷¹⁹²¹ is an apocalyptic number.

It is an amenable number.

671921 is a deficient number, since it is larger than the sum of its proper divisors (1).

671921 is an equidigital number, since it uses as much as digits as its factorization.

671921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 756, while the sum is 26.

The square root of 671921 is about 819.7078747944. The cubic root of 671921 is about 87.5869503020.

The spelling of 671921 in words is "six hundred seventy-one thousand, nine hundred twenty-one".