616520321 has 4 divisors (see below), whose sum is σ = 631557444. Its totient is φ = 601483200.

The previous prime is 616520287. The next prime is 616520329. The reversal of 616520321 is 123025616.

616520321 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 124567921 + 491952400 = 11161^2 + 22180^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-616520321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (616520329) 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, 7518500 + ... + 7518581.

It is an arithmetic number, because the mean of its divisors is an integer number (157889361).

Almost surely, 2^616520321 is an apocalyptic number.

It is an amenable number.

616520321 is a deficient number, since it is larger than the sum of its proper divisors (15037123).

616520321 is a wasteful number, since it uses less digits than its factorization.

616520321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15037122.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 616520321 is about 24829.8272446668. The cubic root of 616520321 is about 851.1036740529.

Adding to 616520321 its reverse (123025616), we get a palindrome (739545937).

The spelling of 616520321 in words is "six hundred sixteen million, five hundred twenty thousand, three hundred twenty-one".