81557004 has 12 divisors (see below), whose sum is σ = 190299704. Its totient is φ = 27185664.

The previous prime is 81556967. The next prime is 81557009. The reversal of 81557004 is 40075518.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (81557009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3398197 + ... + 3398220.

Almost surely, 2^81557004 is an apocalyptic number.

It is an amenable number.

81557004 is an abundant number, since it is smaller than the sum of its proper divisors (108742700).

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

81557004 is a wasteful number, since it uses less digits than its factorization.

81557004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6796424 (or 6796422 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 30.

The square root of 81557004 is about 9030.8916503300. The cubic root of 81557004 is about 433.6643826616.

The spelling of 81557004 in words is "eighty-one million, five hundred fifty-seven thousand, four".