81686650 has 24 divisors (see below), whose sum is σ = 152802720. Its totient is φ = 32488560.

The previous prime is 81686617. The next prime is 81686651. The reversal of 81686650 is 5668618.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81686651) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4387 + ... + 13513.

It is an arithmetic number, because the mean of its divisors is an integer number (6366780).

Almost surely, 2^81686650 is an apocalyptic number.

81686650 is a deficient number, since it is larger than the sum of its proper divisors (71116070).

81686650 is a wasteful number, since it uses less digits than its factorization.

81686650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9318 (or 9313 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 40.

The square root of 81686650 is about 9038.0667180543. The cubic root of 81686650 is about 433.8940506025.

The spelling of 81686650 in words is "eighty-one million, six hundred eighty-six thousand, six hundred fifty".