81125919337 has 4 divisors (see below), whose sum is σ = 81745201296. Its totient is φ = 80506637380.

The previous prime is 81125919323. The next prime is 81125919349. The reversal of 81125919337 is 73391952118.

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 81125919337 - 2⁷ = 81125919209 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81125919367) 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, 309640783 + ... + 309641044.

It is an arithmetic number, because the mean of its divisors is an integer number (20436300324).

Almost surely, 2^81125919337 is an apocalyptic number.

It is an amenable number.

81125919337 is a deficient number, since it is larger than the sum of its proper divisors (619281959).

81125919337 is a wasteful number, since it uses less digits than its factorization.

81125919337 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 619281958.

The product of its digits is 408240, while the sum is 49.

The spelling of 81125919337 in words is "eighty-one billion, one hundred twenty-five million, nine hundred nineteen thousand, three hundred thirty-seven".