81686715 has 16 divisors (see below), whose sum is σ = 142580736. Its totient is φ = 39605600.

The previous prime is 81686701. The next prime is 81686729. The reversal of 81686715 is 51768618.

It is an interprime number because it is at equal distance from previous prime (81686701) and next prime (81686729).

It is not a de Polignac number, because 81686715 - 2⁴ = 81686699 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 247371 + ... + 247700.

It is an arithmetic number, because the mean of its divisors is an integer number (8911296).

Almost surely, 2^81686715 is an apocalyptic number.

81686715 is a deficient number, since it is larger than the sum of its proper divisors (60894021).

81686715 is a wasteful number, since it uses less digits than its factorization.

81686715 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495090.

The product of its digits is 80640, while the sum is 42.

The square root of 81686715 is about 9038.0703139553. The cubic root of 81686715 is about 433.8941656891.

The spelling of 81686715 in words is "eighty-one million, six hundred eighty-six thousand, seven hundred fifteen".