616721 has 8 divisors (see below), whose sum is σ = 742080. Its totient is φ = 500688.

The previous prime is 616717. The next prime is 616723. The reversal of 616721 is 127616.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 616721 - 2² = 616717 is a prime.

It is an Ulam number.

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

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 616721.

It is not an unprimeable number, because it can be changed into a prime (616723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2186 + ... + 2451.

It is an arithmetic number, because the mean of its divisors is an integer number (92760).

2⁶¹⁶⁷²¹ is an apocalyptic number.

It is an amenable number.

616721 is a deficient number, since it is larger than the sum of its proper divisors (125359).

616721 is a wasteful number, since it uses less digits than its factorization.

616721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4663.

The product of its digits is 504, while the sum is 23.

The square root of 616721 is about 785.3158600207. The cubic root of 616721 is about 85.1196009536.

The spelling of 616721 in words is "six hundred sixteen thousand, seven hundred twenty-one".