81447428 has 24 divisors (see below), whose sum is σ = 150595200. Its totient is φ = 38480288.

The previous prime is 81447427. The next prime is 81447463. The reversal of 81447428 is 82474418.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 81447391 and 81447400.

It is not an unprimeable number, because it can be changed into a prime (81447427) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 2018 + ... + 12921.

It is an arithmetic number, because the mean of its divisors is an integer number (6274800).

Almost surely, 2^81447428 is an apocalyptic number.

It is an amenable number.

81447428 is a deficient number, since it is larger than the sum of its proper divisors (69147772).

81447428 is a wasteful number, since it uses less digits than its factorization.

81447428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15019 (or 15017 counting only the distinct ones).

The product of its digits is 57344, while the sum is 38.

The square root of 81447428 is about 9024.8228791484. The cubic root of 81447428 is about 433.4700788681.

The spelling of 81447428 in words is "eighty-one million, four hundred forty-seven thousand, four hundred twenty-eight".