81685502 has 4 divisors (see below), whose sum is σ = 122528256. Its totient is φ = 40842750.

The previous prime is 81685501. The next prime is 81685507. The reversal of 81685502 is 20558618.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81685501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20421374 + ... + 20421377.

It is an arithmetic number, because the mean of its divisors is an integer number (30632064).

Almost surely, 2^81685502 is an apocalyptic number.

81685502 is a deficient number, since it is larger than the sum of its proper divisors (40842754).

81685502 is a wasteful number, since it uses less digits than its factorization.

81685502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40842753.

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 81685502 is about 9038.0032086739. The cubic root of 81685502 is about 433.8920179868.

The spelling of 81685502 in words is "eighty-one million, six hundred eighty-five thousand, five hundred two".