81424915 has 32 divisors (see below), whose sum is σ = 117282816. Its totient is φ = 53477760.

The previous prime is 81424891. The next prime is 81424919. The reversal of 81424915 is 51942418.

It is a happy number.

It is not a de Polignac number, because 81424915 - 2¹⁹ = 80900627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81424919) 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 31 ways as a sum of consecutive naturals, for example, 32394 + ... + 34816.

It is an arithmetic number, because the mean of its divisors is an integer number (3665088).

Almost surely, 2^81424915 is an apocalyptic number.

81424915 is a deficient number, since it is larger than the sum of its proper divisors (35857901).

81424915 is a wasteful number, since it uses less digits than its factorization.

81424915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2499.

The product of its digits is 11520, while the sum is 34.

The square root of 81424915 is about 9023.5755108493. The cubic root of 81424915 is about 433.4301364930.

The spelling of 81424915 in words is "eighty-one million, four hundred twenty-four thousand, nine hundred fifteen".