81625617 has 16 divisors (see below), whose sum is σ = 121733760. Its totient is φ = 54054000.

The previous prime is 81625613. The next prime is 81625637. The reversal of 81625617 is 71652618.

81625617 is a `hidden beast` number, since 8 + 16 + 25 + 617 = 666.

It is not a de Polignac number, because 81625617 - 2² = 81625613 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81625613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5934 + ... + 14087.

It is an arithmetic number, because the mean of its divisors is an integer number (7608360).

Almost surely, 2^81625617 is an apocalyptic number.

It is an amenable number.

81625617 is a deficient number, since it is larger than the sum of its proper divisors (40108143).

81625617 is a wasteful number, since it uses less digits than its factorization.

81625617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20181 (or 20175 counting only the distinct ones).

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

The square root of 81625617 is about 9034.6896460255. The cubic root of 81625617 is about 433.7859609138.

It can be divided in two parts, 8 and 1625617, that added together give a square (1625625 = 1275²).

The spelling of 81625617 in words is "eighty-one million, six hundred twenty-five thousand, six hundred seventeen".