81271290749 has 4 divisors (see below), whose sum is σ = 88659589920. Its totient is φ = 73882991580.

The previous prime is 81271290743. The next prime is 81271290761. The reversal of 81271290749 is 94709217218.

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.

It is a cyclic number.

It is not a de Polignac number, because 81271290749 - 2⁸ = 81271290493 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81271290697 and 81271290706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81271290743) 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, 3694149569 + ... + 3694149590.

It is an arithmetic number, because the mean of its divisors is an integer number (22164897480).

Almost surely, 2^81271290749 is an apocalyptic number.

It is an amenable number.

81271290749 is a deficient number, since it is larger than the sum of its proper divisors (7388299171).

81271290749 is a wasteful number, since it uses less digits than its factorization.

81271290749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7388299170.

The product of its (nonzero) digits is 508032, while the sum is 50.

The spelling of 81271290749 in words is "eighty-one billion, two hundred seventy-one million, two hundred ninety thousand, seven hundred forty-nine".