673345721 has 4 divisors (see below), whose sum is σ = 691544292. Its totient is φ = 655147152.

The previous prime is 673345681. The next prime is 673345763. The reversal of 673345721 is 127543376.

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 441210025 + 232135696 = 21005^2 + 15236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-673345721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (673345781) 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, 9099230 + ... + 9099303.

It is an arithmetic number, because the mean of its divisors is an integer number (172886073).

Almost surely, 2^673345721 is an apocalyptic number.

It is an amenable number.

673345721 is a deficient number, since it is larger than the sum of its proper divisors (18198571).

673345721 is a wasteful number, since it uses less digits than its factorization.

673345721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18198570.

The product of its digits is 105840, while the sum is 38.

The square root of 673345721 is about 25948.9059692311. The cubic root of 673345721 is about 876.4881217417.

The spelling of 673345721 in words is "six hundred seventy-three million, three hundred forty-five thousand, seven hundred twenty-one".