81705100 has 18 divisors (see below), whose sum is σ = 177300284. Its totient is φ = 32682000.

The previous prime is 81705089. The next prime is 81705109. The reversal of 81705100 is 150718.

It is not an unprimeable number, because it can be changed into a prime (81705109) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 408426 + ... + 408625.

Almost surely, 2^81705100 is an apocalyptic number.

It is an amenable number.

81705100 is an abundant number, since it is smaller than the sum of its proper divisors (95595184).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81705100 is a wasteful number, since it uses less digits than its factorization.

81705100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817065 (or 817058 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 22.

The square root of 81705100 is about 9039.0873433107. The cubic root of 81705100 is about 433.9267150286.

Adding to 81705100 its reverse (150718), we get a palindrome (81855818).

The spelling of 81705100 in words is "eighty-one million, seven hundred five thousand, one hundred".