81187263 has 12 divisors (see below), whose sum is σ = 122369520. Its totient is φ = 51771456.

The previous prime is 81187261. The next prime is 81187277. The reversal of 81187263 is 36278118.

It is not a de Polignac number, because 81187263 - 2¹ = 81187261 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81187261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 195898 + ... + 196311.

It is an arithmetic number, because the mean of its divisors is an integer number (10197460).

Almost surely, 2^81187263 is an apocalyptic number.

81187263 is a deficient number, since it is larger than the sum of its proper divisors (41182257).

81187263 is a wasteful number, since it uses less digits than its factorization.

81187263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392238 (or 392235 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 81187263 is about 9010.3974940066. The cubic root of 81187263 is about 433.0080465448.

The spelling of 81187263 in words is "eighty-one million, one hundred eighty-seven thousand, two hundred sixty-three".