81388432 has 30 divisors (see below), whose sum is σ = 160014498. Its totient is φ = 40098816.

The previous prime is 81388429. The next prime is 81388441. The reversal of 81388432 is 23488318.

It can be written as a sum of positive squares in 3 ways, for example, as 48944016 + 32444416 = 6996^2 + 5696^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81388391 and 81388400.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 355294 + ... + 355522.

Almost surely, 2^81388432 is an apocalyptic number.

It is an amenable number.

81388432 is a deficient number, since it is larger than the sum of its proper divisors (78626066).

81388432 is an equidigital number, since it uses as much as digits as its factorization.

81388432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563 (or 328 counting only the distinct ones).

The product of its digits is 36864, while the sum is 37.

The square root of 81388432 is about 9021.5537464452. The cubic root of 81388432 is about 433.3653930258.

The spelling of 81388432 in words is "eighty-one million, three hundred eighty-eight thousand, four hundred thirty-two".