670921 has 4 divisors (see below), whose sum is σ = 689092. Its totient is φ = 652752.

The previous prime is 670919. The next prime is 670931. The reversal of 670921 is 129076.

670921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 455625 + 215296 = 675^2 + 464^2 .

It is a cyclic number.

It is not a de Polignac number, because 670921 - 2¹ = 670919 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (670931) 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, 9030 + ... + 9103.

It is an arithmetic number, because the mean of its divisors is an integer number (172273).

2⁶⁷⁰⁹²¹ is an apocalyptic number.

It is an amenable number.

670921 is a deficient number, since it is larger than the sum of its proper divisors (18171).

670921 is a wasteful number, since it uses less digits than its factorization.

670921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18170.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 670921 is about 819.0976742733. The cubic root of 670921 is about 87.5434777126.

Adding to 670921 its reverse (129076), we get a palindrome (799997).

The spelling of 670921 in words is "six hundred seventy thousand, nine hundred twenty-one".