81904015 has 8 divisors (see below), whose sum is σ = 101455488. Its totient is φ = 63409440.

The previous prime is 81904013. The next prime is 81904057. The reversal of 81904015 is 51040918.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81904015 - 2¹ = 81904013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81904013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 264052 + ... + 264361.

It is an arithmetic number, because the mean of its divisors is an integer number (12681936).

Almost surely, 2^81904015 is an apocalyptic number.

81904015 is a deficient number, since it is larger than the sum of its proper divisors (19551473).

81904015 is a wasteful number, since it uses less digits than its factorization.

81904015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528449.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 81904015 is about 9050.0837012704. The cubic root of 81904015 is about 434.2785681421.

The spelling of 81904015 in words is "eighty-one million, nine hundred four thousand, fifteen".