81956560 has 80 divisors (see below), whose sum is σ = 224842752. Its totient is φ = 27187200.

The previous prime is 81956549. The next prime is 81956569. The reversal of 81956560 is 6565918.

It is a tau number, because it is divible by the number of its divisors (80).

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 (81956569) 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, 15000 + ... + 19720.

Almost surely, 2^81956560 is an apocalyptic number.

81956560 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81956560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112421376).

81956560 is an abundant number, since it is smaller than the sum of its proper divisors (142886192).

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

81956560 is a wasteful number, since it uses less digits than its factorization.

81956560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4772 (or 4766 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 40.

The square root of 81956560 is about 9052.9862476423. The cubic root of 81956560 is about 434.3714178405.

The spelling of 81956560 in words is "eighty-one million, nine hundred fifty-six thousand, five hundred sixty".