81855004 has 48 divisors (see below), whose sum is σ = 184375296. Its totient is φ = 30859200.

The previous prime is 81854987. The next prime is 81855013. The reversal of 81855004 is 40055818.

81855004 = T₁₂₈₀ + T₁₂₈₁ + ... + T₁₃₇₂.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5262 + ... + 13834.

It is an arithmetic number, because the mean of its divisors is an integer number (3841152).

Almost surely, 2^81855004 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81855004, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92187648).

81855004 is an abundant number, since it is smaller than the sum of its proper divisors (102520292).

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

81855004 is a wasteful number, since it uses less digits than its factorization.

81855004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8626 (or 8624 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 81855004 is about 9047.3755310587. The cubic root of 81855004 is about 434.1919274004.

The spelling of 81855004 in words is "eighty-one million, eight hundred fifty-five thousand, four".