81687837 has 16 divisors (see below), whose sum is σ = 135793152. Its totient is φ = 42435120.

The previous prime is 81687811. The next prime is 81687841. The reversal of 81687837 is 73878618.

It is not a de Polignac number, because 81687837 - 2⁶ = 81687773 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81687847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 176583 + ... + 177044.

It is an arithmetic number, because the mean of its divisors is an integer number (8487072).

Almost surely, 2^81687837 is an apocalyptic number.

It is an amenable number.

81687837 is a deficient number, since it is larger than the sum of its proper divisors (54105315).

81687837 is a wasteful number, since it uses less digits than its factorization.

81687837 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353648.

The product of its digits is 451584, while the sum is 48.

The square root of 81687837 is about 9038.1323845140. The cubic root of 81687837 is about 433.8961522505.

The spelling of 81687837 in words is "eighty-one million, six hundred eighty-seven thousand, eight hundred thirty-seven".