81625599 has 12 divisors (see below), whose sum is σ = 128622312. Its totient is φ = 49470000.

The previous prime is 81625541. The next prime is 81625601. The reversal of 81625599 is 99552618.

It is not a de Polignac number, because 81625599 - 2⁹ = 81625087 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81625519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 412152 + ... + 412349.

It is an arithmetic number, because the mean of its divisors is an integer number (10718526).

Almost surely, 2^81625599 is an apocalyptic number.

81625599 is a deficient number, since it is larger than the sum of its proper divisors (46996713).

81625599 is a wasteful number, since it uses less digits than its factorization.

81625599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 824518 (or 824515 counting only the distinct ones).

The product of its digits is 194400, while the sum is 45.

The square root of 81625599 is about 9034.6886498650. The cubic root of 81625599 is about 433.7859290278.

The spelling of 81625599 in words is "eighty-one million, six hundred twenty-five thousand, five hundred ninety-nine".