81420736 has 28 divisors (see below), whose sum is σ = 168597072. Its totient is φ = 38939648.

The previous prime is 81420727. The next prime is 81420751. The reversal of 81420736 is 63702418.

It is a junction number, because it is equal to n+sod(n) for n = 81420698 and 81420707.

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 3 ways as a sum of consecutive naturals, for example, 26185 + ... + 29128.

It is an arithmetic number, because the mean of its divisors is an integer number (6021324).

Almost surely, 2^81420736 is an apocalyptic number.

It is an amenable number.

81420736 is an abundant number, since it is smaller than the sum of its proper divisors (87176336).

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

81420736 is a wasteful number, since it uses less digits than its factorization.

81420736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55348 (or 55338 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 81420736 is about 9023.3439477834. The cubic root of 81420736 is about 433.4227213362.

The spelling of 81420736 in words is "eighty-one million, four hundred twenty thousand, seven hundred thirty-six".