81011280 has 80 divisors (see below), whose sum is σ = 287017344. Its totient is φ = 18516480.

The previous prime is 81011279. The next prime is 81011299. The reversal of 81011280 is 8211018.

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 (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22431 + ... + 25790.

Almost surely, 2^81011280 is an apocalyptic number.

81011280 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81011280 is an abundant number, since it is smaller than the sum of its proper divisors (206006064).

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

81011280 is a wasteful number, since it uses less digits than its factorization.

81011280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48244 (or 48238 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 81011280 is about 9000.6266448509. The cubic root of 81011280 is about 432.6949548207.

Adding to 81011280 its reverse (8211018), we get a palindrome (89222298).

It can be divided in two parts, 810 and 11280, that added together give a triangular number (12090 = T₁₅₅).

The spelling of 81011280 in words is "eighty-one million, eleven thousand, two hundred eighty".