1613521813 has 4 divisors (see below), whose sum is σ = 1623799180. Its totient is φ = 1603244448.

The previous prime is 1613521787. The next prime is 1613521817. The reversal of 1613521813 is 3181253161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3181253161 = 193 ⋅16483177.

It can be written as a sum of positive squares in 2 ways, for example, as 1212641329 + 400880484 = 34823^2 + 20022^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1613521813 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 (1613521817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5138448 + ... + 5138761.

It is an arithmetic number, because the mean of its divisors is an integer number (405949795).

Almost surely, 2^1613521813 is an apocalyptic number.

It is an amenable number.

1613521813 is a deficient number, since it is larger than the sum of its proper divisors (10277367).

1613521813 is a wasteful number, since it uses less digits than its factorization.

1613521813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10277366.

The product of its digits is 4320, while the sum is 31.

The square root of 1613521813 is about 40168.6670553057. The cubic root of 1613521813 is about 1172.8926920115.

Adding to 1613521813 its reverse (3181253161), we get a palindrome (4794774974).

The spelling of 1613521813 in words is "one billion, six hundred thirteen million, five hundred twenty-one thousand, eight hundred thirteen".