81475687 has 4 divisors (see below), whose sum is σ = 82811416. Its totient is φ = 80139960.

The previous prime is 81475649. The next prime is 81475697. The reversal of 81475687 is 78657418.

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 81475687 - 2¹⁵ = 81442919 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81475627) 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, 667773 + ... + 667894.

It is an arithmetic number, because the mean of its divisors is an integer number (20702854).

Almost surely, 2^81475687 is an apocalyptic number.

81475687 is a deficient number, since it is larger than the sum of its proper divisors (1335729).

81475687 is a wasteful number, since it uses less digits than its factorization.

81475687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1335728.

The product of its digits is 376320, while the sum is 46.

The square root of 81475687 is about 9026.3883696637. The cubic root of 81475687 is about 433.5202053315.

The spelling of 81475687 in words is "eighty-one million, four hundred seventy-five thousand, six hundred eighty-seven".