81559280 has 40 divisors (see below), whose sum is σ = 206866224. Its totient is φ = 29657600.

The previous prime is 81559277. The next prime is 81559297. The reversal of 81559280 is 8295518.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45461 + ... + 47220.

Almost surely, 2^81559280 is an apocalyptic number.

81559280 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81559280 is an abundant number, since it is smaller than the sum of its proper divisors (125306944).

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

81559280 is a wasteful number, since it uses less digits than its factorization.

81559280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92705 (or 92699 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 38.

The square root of 81559280 is about 9031.0176613713. The cubic root of 81559280 is about 433.6684166947.

The spelling of 81559280 in words is "eighty-one million, five hundred fifty-nine thousand, two hundred eighty".