1516723321 has 2 divisors, whose sum is σ = 1516723322. Its totient is φ = 1516723320.

The previous prime is 1516723319. The next prime is 1516723343. The reversal of 1516723321 is 1233276151.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1405125225 + 111598096 = 37485^2 + 10564^2 .

It is an emirp because it is prime and its reverse (1233276151) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1516723321 - 2¹ = 1516723319 is a prime.

It is a super-4 number, since 4×1516723321⁴ (a number of 38 digits) contains 4444 as substring.

Together with 1516723319, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1516723361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 758361660 + 758361661.

It is an arithmetic number, because the mean of its divisors is an integer number (758361661).

Almost surely, 2^1516723321 is an apocalyptic number.

It is an amenable number.

1516723321 is a deficient number, since it is larger than the sum of its proper divisors (1).

1516723321 is an equidigital number, since it uses as much as digits as its factorization.

1516723321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 31.

The square root of 1516723321 is about 38945.1321861924. The cubic root of 1516723321 is about 1148.9526244523.

Adding to 1516723321 its reverse (1233276151), we get a palindrome (2749999472).

The spelling of 1516723321 in words is "one billion, five hundred sixteen million, seven hundred twenty-three thousand, three hundred twenty-one".