81737416181 has 4 divisors (see below), whose sum is σ = 81738003264. Its totient is φ = 81736829100.

The previous prime is 81737416153. The next prime is 81737416217. The reversal of 81737416181 is 18161473718.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18161473718 = 2 ⋅9080736859.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81737416181 is a prime.

It is a super-2 number, since 2×81737416181² (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 (81737412181) 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, 46946 + ... + 407036.

It is an arithmetic number, because the mean of its divisors is an integer number (20434500816).

Almost surely, 2^81737416181 is an apocalyptic number.

It is an amenable number.

81737416181 is a deficient number, since it is larger than the sum of its proper divisors (587083).

81737416181 is a wasteful number, since it uses less digits than its factorization.

81737416181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 587082.

The product of its digits is 225792, while the sum is 47.

Adding to 81737416181 its reverse (18161473718), we get a palindrome (99898889899).

The spelling of 81737416181 in words is "eighty-one billion, seven hundred thirty-seven million, four hundred sixteen thousand, one hundred eighty-one".