81655280 has 80 divisors (see below), whose sum is σ = 222081024. Its totient is φ = 27336960.

The previous prime is 81655253. The next prime is 81655283. The reversal of 81655280 is 8255618.

It is a happy number.

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

It is a super-3 number, since 3×81655280³ (a number of 25 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 81655280.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81655283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22385 + ... + 25775.

Almost surely, 2^81655280 is an apocalyptic number.

81655280 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 81655280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111040512).

81655280 is an abundant number, since it is smaller than the sum of its proper divisors (140425744).

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

81655280 is a wasteful number, since it uses less digits than its factorization.

81655280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3454 (or 3448 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 81655280 is about 9036.3311138979. The cubic root of 81655280 is about 433.8385009335.

The spelling of 81655280 in words is "eighty-one million, six hundred fifty-five thousand, two hundred eighty".