81420424 has 32 divisors (see below), whose sum is σ = 160637400. Its totient is φ = 38638080.

The previous prime is 81420419. The next prime is 81420431. The reversal of 81420424 is 42402418.

It can be written as a sum of positive squares in 4 ways, for example, as 71064900 + 10355524 = 8430^2 + 3218^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8782 + ... + 15490.

Almost surely, 2^81420424 is an apocalyptic number.

It is an amenable number.

81420424 is a deficient number, since it is larger than the sum of its proper divisors (79216976).

81420424 is a wasteful number, since it uses less digits than its factorization.

81420424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6793 (or 6789 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 25.

The square root of 81420424 is about 9023.3266592759. The cubic root of 81420424 is about 433.4221677178.

The spelling of 81420424 in words is "eighty-one million, four hundred twenty thousand, four hundred twenty-four".