81493364261 has 8 divisors (see below), whose sum is σ = 84399197400. Its totient is φ = 78593912320.

The previous prime is 81493364221. The next prime is 81493364269. The reversal of 81493364261 is 16246339418.

It can be written as a sum of positive squares in 4 ways, for example, as 6359265025 + 75134099236 = 79745^2 + 274106^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81493364261 - 2¹⁴ = 81493347877 is a prime.

It is a super-2 number, since 2×81493364261² (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 (81493364269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1569296 + ... + 1620393.

It is an arithmetic number, because the mean of its divisors is an integer number (10549899675).

Almost surely, 2^81493364261 is an apocalyptic number.

It is an amenable number.

81493364261 is a deficient number, since it is larger than the sum of its proper divisors (2905833139).

81493364261 is a wasteful number, since it uses less digits than its factorization.

81493364261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3190599.

The product of its digits is 746496, while the sum is 47.

The spelling of 81493364261 in words is "eighty-one billion, four hundred ninety-three million, three hundred sixty-four thousand, two hundred sixty-one".