81569037820 has 24 divisors (see below), whose sum is σ = 171300351600. Its totient is φ = 32626591872.

The previous prime is 81569037799. The next prime is 81569037829. The reversal of 81569037820 is 2873096518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81569037829) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1177096 + ... + 1244464.

It is an arithmetic number, because the mean of its divisors is an integer number (7137514650).

Almost surely, 2^81569037820 is an apocalyptic number.

It is an amenable number.

81569037820 is an abundant number, since it is smaller than the sum of its proper divisors (89731313780).

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

81569037820 is a wasteful number, since it uses less digits than its factorization.

81569037820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127917 (or 127915 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 81569037820 in words is "eighty-one billion, five hundred sixty-nine million, thirty-seven thousand, eight hundred twenty".