81387895 has 4 divisors (see below), whose sum is σ = 97665480. Its totient is φ = 65110312.

The previous prime is 81387893. The next prime is 81387923. The reversal of 81387895 is 59878318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81387895 - 2¹ = 81387893 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 congruent number.

It is not an unprimeable number, because it can be changed into a prime (81387893) 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, 8138785 + ... + 8138794.

It is an arithmetic number, because the mean of its divisors is an integer number (24416370).

Almost surely, 2^81387895 is an apocalyptic number.

81387895 is a deficient number, since it is larger than the sum of its proper divisors (16277585).

81387895 is a wasteful number, since it uses less digits than its factorization.

81387895 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16277584.

The product of its digits is 483840, while the sum is 49.

The square root of 81387895 is about 9021.5239843388. The cubic root of 81387895 is about 433.3644399103.

The spelling of 81387895 in words is "eighty-one million, three hundred eighty-seven thousand, eight hundred ninety-five".