671531921 has 2 divisors, whose sum is σ = 671531922. Its totient is φ = 671531920.

The previous prime is 671531899. The next prime is 671531929. The reversal of 671531921 is 129135176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 569299600 + 102232321 = 23860^2 + 10111^2 .

It is a cyclic number.

It is not a de Polignac number, because 671531921 - 2⁶ = 671531857 is a prime.

It is not a weakly prime, because it can be changed into another prime (671531929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335765960 + 335765961.

It is an arithmetic number, because the mean of its divisors is an integer number (335765961).

Almost surely, 2^671531921 is an apocalyptic number.

It is an amenable number.

671531921 is a deficient number, since it is larger than the sum of its proper divisors (1).

671531921 is an equidigital number, since it uses as much as digits as its factorization.

671531921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11340, while the sum is 35.

The square root of 671531921 is about 25913.9329512137. The cubic root of 671531921 is about 875.7004115998.

The spelling of 671531921 in words is "six hundred seventy-one million, five hundred thirty-one thousand, nine hundred twenty-one".