81424404 has 18 divisors (see below), whose sum is σ = 205822890. Its totient is φ = 27141456.

The previous prime is 81424397. The next prime is 81424423. The reversal of 81424404 is 40442418.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 79174404 + 2250000 = 8898^2 + 1500^2 .

It is a tau number, because it is divible by the number of its divisors (18).

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 5 ways as a sum of consecutive naturals, for example, 1130859 + ... + 1130930.

It is an arithmetic number, because the mean of its divisors is an integer number (11434605).

Almost surely, 2^81424404 is an apocalyptic number.

It is an amenable number.

81424404 is an abundant number, since it is smaller than the sum of its proper divisors (124398486).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81424404 is a wasteful number, since it uses less digits than its factorization.

81424404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2261799 (or 2261794 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 27.

The square root of 81424404 is about 9023.5471960865. The cubic root of 81424404 is about 433.4292297957.

The spelling of 81424404 in words is "eighty-one million, four hundred twenty-four thousand, four hundred four".