1516721517 has 10 divisors (see below), whose sum is σ = 2265719918. Its totient is φ = 1011147624.

The previous prime is 1516721513. The next prime is 1516721519. The reversal of 1516721517 is 7151276151.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1088604036 + 428117481 = 32994^2 + 20691^2 .

It is not a de Polignac number, because 1516721517 - 2² = 1516721513 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1516721513) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 9362398 + ... + 9362559.

Almost surely, 2^1516721517 is an apocalyptic number.

It is an amenable number.

1516721517 is a deficient number, since it is larger than the sum of its proper divisors (748998401).

1516721517 is an equidigital number, since it uses as much as digits as its factorization.

1516721517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18724969 (or 18724960 counting only the distinct ones).

The product of its digits is 14700, while the sum is 36.

The square root of 1516721517 is about 38945.1090253962. The cubic root of 1516721517 is about 1148.9521689283.

Adding to 1516721517 its reverse (7151276151), we get a palindrome (8667997668).

The spelling of 1516721517 in words is "one billion, five hundred sixteen million, seven hundred twenty-one thousand, five hundred seventeen".