81138145 has 8 divisors (see below), whose sum is σ = 106217280. Its totient is φ = 59009520.

The previous prime is 81138133. The next prime is 81138149. The reversal of 81138145 is 54183118.

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

It is not a de Polignac number, because 81138145 - 2²¹ = 79040993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81138149) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 737565 + ... + 737674.

It is an arithmetic number, because the mean of its divisors is an integer number (13277160).

Almost surely, 2^81138145 is an apocalyptic number.

It is an amenable number.

81138145 is a deficient number, since it is larger than the sum of its proper divisors (25079135).

81138145 is a wasteful number, since it uses less digits than its factorization.

81138145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1475255.

The product of its digits is 3840, while the sum is 31.

The square root of 81138145 is about 9007.6714527118. The cubic root of 81138145 is about 432.9207061624.

The spelling of 81138145 in words is "eighty-one million, one hundred thirty-eight thousand, one hundred forty-five".