81340394869881 has 315 divisors, whose sum is σ = 151511209816253. Its totient is φ = 43637002214400.

The previous prime is 81340394869841. The next prime is 81340394869897. The reversal of 81340394869881 is 18896849304318.

The square root of 81340394869881 is 9018891.

It is a perfect power (a square), and thus also a powerful number.

81340394869881 is a `hidden beast` number, since 8 + 1 + 34 + 0 + 39 + 486 + 9 + 8 + 81 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 56171952092025 + 25168442777856 = 7494795^2 + 5016816^2 .

It is not a de Polignac number, because 81340394869881 - 2¹³ = 81340394861689 is a prime.

It is a super-2 number, since 2×81340394869881² (a number of 29 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (72) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81340394869841) by changing a digit.

It is a polite number, since it can be written in 314 ways as a sum of consecutive naturals, for example, 202843877281 + ... + 202843877681.

Almost surely, 2^{81340394869881} is an apocalyptic number.

81340394869881 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81340394869881 is the 9018891-st square number.

81340394869881 is the 4509446-th centered octagonal number.

It is an amenable number.

81340394869881 is a deficient number, since it is larger than the sum of its proper divisors (70170814946372).

81340394869881 is an frugal number, since it uses more digits than its factorization.

81340394869881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 882 (or 428 counting only the distinct ones).

The product of its (nonzero) digits is 286654464, while the sum is 72.

The spelling of 81340394869881 in words is "eighty-one trillion, three hundred forty billion, three hundred ninety-four million, eight hundred sixty-nine thousand, eight hundred eighty-one".