81569004 has 48 divisors (see below), whose sum is σ = 209387136. Its totient is φ = 24713040.

The previous prime is 81569003. The next prime is 81569011. The reversal of 81569004 is 40096518.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (81569003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13419 + ... + 18525.

It is an arithmetic number, because the mean of its divisors is an integer number (4362232).

Almost surely, 2^81569004 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 81569004, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104693568).

81569004 is an abundant number, since it is smaller than the sum of its proper divisors (127818132).

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

81569004 is a wasteful number, since it uses less digits than its factorization.

81569004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5147 (or 5123 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 81569004 is about 9031.5560121166. The cubic root of 81569004 is about 433.6856508835.

The spelling of 81569004 in words is "eighty-one million, five hundred sixty-nine thousand, four".