81397424 has 20 divisors (see below), whose sum is σ = 160294800. Its totient is φ = 40031040.

The previous prime is 81397417. The next prime is 81397439. The reversal of 81397424 is 42479318.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 40724 + ... + 42675.

It is an arithmetic number, because the mean of its divisors is an integer number (8014740).

Almost surely, 2^81397424 is an apocalyptic number.

It is an amenable number.

81397424 is a deficient number, since it is larger than the sum of its proper divisors (78897376).

81397424 is a wasteful number, since it uses less digits than its factorization.

81397424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83468 (or 83462 counting only the distinct ones).

The product of its digits is 48384, while the sum is 38.

The square root of 81397424 is about 9022.0520947288. The cubic root of 81397424 is about 433.3813522066.

The spelling of 81397424 in words is "eighty-one million, three hundred ninety-seven thousand, four hundred twenty-four".