81842420560 has 20 divisors (see below), whose sum is σ = 190283627988. Its totient is φ = 32736968192.

The previous prime is 81842420549. The next prime is 81842420563. The reversal of 81842420560 is 6502424818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 55335975696 + 26506444864 = 235236^2 + 162808^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81842420563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 511515049 + ... + 511515208.

Almost surely, 2^81842420560 is an apocalyptic number.

81842420560 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81842420560 is an abundant number, since it is smaller than the sum of its proper divisors (108441207428).

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

81842420560 is a wasteful number, since it uses less digits than its factorization.

81842420560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023030270 (or 1023030264 counting only the distinct ones).

The product of its (nonzero) digits is 122880, while the sum is 40.

The spelling of 81842420560 in words is "eighty-one billion, eight hundred forty-two million, four hundred twenty thousand, five hundred sixty".