81924005569 has 12 divisors (see below), whose sum is σ = 96281826564. Its totient is φ = 69496648704.

The previous prime is 81924005551. The next prime is 81924005623. The reversal of 81924005569 is 96550042918.

It can be written as a sum of positive squares in 2 ways, for example, as 64264785025 + 17659220544 = 253505^2 + 132888^2 .

It is not a de Polignac number, because 81924005569 - 2¹⁹ = 81923481281 is a prime.

It is a super-2 number, since 2×81924005569² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is not an unprimeable number, because it can be changed into a prime (81924005539) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8613384 + ... + 8622889.

It is an arithmetic number, because the mean of its divisors is an integer number (8023485547).

Almost surely, 2^81924005569 is an apocalyptic number.

It is an amenable number.

81924005569 is a deficient number, since it is larger than the sum of its proper divisors (14357820995).

81924005569 is a wasteful number, since it uses less digits than its factorization.

81924005569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17236384 (or 17236377 counting only the distinct ones).

The product of its (nonzero) digits is 777600, while the sum is 49.

The spelling of 81924005569 in words is "eighty-one billion, nine hundred twenty-four million, five thousand, five hundred sixty-nine".