609721 has 4 divisors (see below), whose sum is σ = 696832. Its totient is φ = 522612.

The previous prime is 609709. The next prime is 609743. The reversal of 609721 is 127906.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 609721 - 2⁷ = 609593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (609701) 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 in 3 ways as a sum of consecutive naturals, for example, 43545 + ... + 43558.

It is an arithmetic number, because the mean of its divisors is an integer number (174208).

2⁶⁰⁹⁷²¹ is an apocalyptic number.

It is an amenable number.

609721 is a deficient number, since it is larger than the sum of its proper divisors (87111).

609721 is an equidigital number, since it uses as much as digits as its factorization.

609721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87110.

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

The square root of 609721 is about 780.8463357153. The cubic root of 609721 is about 84.7963289766.

The spelling of 609721 in words is "six hundred nine thousand, seven hundred twenty-one".