81949982945 has 16 divisors (see below), whose sum is σ = 99780342480. Its totient is φ = 64605548544.

The previous prime is 81949982909. The next prime is 81949982977. The reversal of 81949982945 is 54928994918.

It can be written as a sum of positive squares in 8 ways, for example, as 7731333184 + 74218649761 = 87928^2 + 272431^2 .

It is a cyclic number.

It is not a de Polignac number, because 81949982945 - 2¹⁰ = 81949981921 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 249590 + ... + 475599.

It is an arithmetic number, because the mean of its divisors is an integer number (6236271405).

Almost surely, 2^81949982945 is an apocalyptic number.

It is an amenable number.

81949982945 is a deficient number, since it is larger than the sum of its proper divisors (17830359535).

81949982945 is a wasteful number, since it uses less digits than its factorization.

81949982945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725524.

The product of its digits is 67184640, while the sum is 68.

The spelling of 81949982945 in words is "eighty-one billion, nine hundred forty-nine million, nine hundred eighty-two thousand, nine hundred forty-five".