81671625 has 64 divisors (see below), whose sum is σ = 172623360. Its totient is φ = 37324800.

The previous prime is 81671599. The next prime is 81671657. The reversal of 81671625 is 52617618.

It is not a de Polignac number, because 81671625 - 2⁶ = 81671561 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81671625.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 21897 + ... + 25353.

It is an arithmetic number, because the mean of its divisors is an integer number (2697240).

Almost surely, 2^81671625 is an apocalyptic number.

It is an amenable number.

81671625 is an abundant number, since it is smaller than the sum of its proper divisors (90951735).

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

81671625 is a wasteful number, since it uses less digits than its factorization.

81671625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3488 (or 3472 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 81671625 is about 9037.2354733071. The cubic root of 81671625 is about 433.8674462641.

The spelling of 81671625 in words is "eighty-one million, six hundred seventy-one thousand, six hundred twenty-five".