81287504 has 20 divisors (see below), whose sum is σ = 157853364. Its totient is φ = 40551168.

The previous prime is 81287467. The next prime is 81287593. The reversal of 81287504 is 40578218.

It can be written as a sum of positive squares in 2 ways, for example, as 39037504 + 42250000 = 6248^2 + 6500^2 .

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a congruent number.

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, 1754 + ... + 12870.

Almost surely, 2^81287504 is an apocalyptic number.

It is an amenable number.

81287504 is a deficient number, since it is larger than the sum of its proper divisors (76565860).

81287504 is a wasteful number, since it uses less digits than its factorization.

81287504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11582 (or 11576 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 81287504 is about 9015.9582962656. The cubic root of 81287504 is about 433.1861833045.

The spelling of 81287504 in words is "eighty-one million, two hundred eighty-seven thousand, five hundred four".