81598819949 has 4 divisors (see below), whose sum is σ = 81612776700. Its totient is φ = 81584863200.

The previous prime is 81598819937. The next prime is 81598819987. The reversal of 81598819949 is 94991889518.

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 64044424900 + 17554395049 = 253070^2 + 132493^2 .

It is a cyclic number.

It is not a de Polignac number, because 81598819949 - 2¹² = 81598815853 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 (81598819849) 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, 6969602 + ... + 6981299.

It is an arithmetic number, because the mean of its divisors is an integer number (20403194175).

Almost surely, 2^81598819949 is an apocalyptic number.

It is an amenable number.

81598819949 is a deficient number, since it is larger than the sum of its proper divisors (13956751).

81598819949 is a wasteful number, since it uses less digits than its factorization.

81598819949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13956750.

The product of its digits is 67184640, while the sum is 71.

The spelling of 81598819949 in words is "eighty-one billion, five hundred ninety-eight million, eight hundred nineteen thousand, nine hundred forty-nine".