81427784 has 16 divisors (see below), whose sum is σ = 152984700. Its totient is φ = 40631872.

The previous prime is 81427747. The next prime is 81427789. The reversal of 81427784 is 48772418.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 70392100 + 11035684 = 8390^2 + 3322^2 .

It is not an unprimeable number, because it can be changed into a prime (81427789) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5927 + ... + 14070.

Almost surely, 2^81427784 is an apocalyptic number.

It is an amenable number.

81427784 is a deficient number, since it is larger than the sum of its proper divisors (71556916).

81427784 is a wasteful number, since it uses less digits than its factorization.

81427784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20512 (or 20508 counting only the distinct ones).

The product of its digits is 100352, while the sum is 41.

The square root of 81427784 is about 9023.7344819094. The cubic root of 81427784 is about 433.4352270580.

The spelling of 81427784 in words is "eighty-one million, four hundred twenty-seven thousand, seven hundred eighty-four".