1815520013 has 2 divisors, whose sum is σ = 1815520014. Its totient is φ = 1815520012.

The previous prime is 1815519967. The next prime is 1815520043. The reversal of 1815520013 is 3100255181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1151787844 + 663732169 = 33938^2 + 25763^2 .

It is a cyclic number.

It is not a de Polignac number, because 1815520013 - 2⁶ = 1815519949 is a prime.

It is a super-2 number, since 2×1815520013² = 6592225835207040338, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1815520043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 907760006 + 907760007.

It is an arithmetic number, because the mean of its divisors is an integer number (907760007).

Almost surely, 2^1815520013 is an apocalyptic number.

It is an amenable number.

1815520013 is a deficient number, since it is larger than the sum of its proper divisors (1).

1815520013 is an equidigital number, since it uses as much as digits as its factorization.

1815520013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1200, while the sum is 26.

The square root of 1815520013 is about 42608.9194066219. The cubic root of 1815520013 is about 1219.9265415324.

Adding to 1815520013 its reverse (3100255181), we get a palindrome (4915775194).

The spelling of 1815520013 in words is "one billion, eight hundred fifteen million, five hundred twenty thousand, thirteen".