81920599069 has 4 divisors (see below), whose sum is σ = 81921315420. Its totient is φ = 81919882720.

The previous prime is 81920599021. The next prime is 81920599081. The reversal of 81920599069 is 96099502918.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 13309083225 + 68611515844 = 115365^2 + 261938^2 .

It is a cyclic number.

It is not a de Polignac number, because 81920599069 - 2¹⁷ = 81920467997 is a prime.

It is a super-2 number, since 2×81920599069² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81920591069) 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, 143914 + ... + 429595.

It is an arithmetic number, because the mean of its divisors is an integer number (20480328855).

Almost surely, 2^81920599069 is an apocalyptic number.

It is an amenable number.

81920599069 is a deficient number, since it is larger than the sum of its proper divisors (716351).

81920599069 is a wasteful number, since it uses less digits than its factorization.

81920599069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 716350.

The product of its (nonzero) digits is 3149280, while the sum is 58.

The spelling of 81920599069 in words is "eighty-one billion, nine hundred twenty million, five hundred ninety-nine thousand, sixty-nine".