81872240 has 40 divisors (see below), whose sum is σ = 196499328. Its totient is φ = 31691520.

The previous prime is 81872237. The next prime is 81872269. The reversal of 81872240 is 4227818.

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

It is a junction number, because it is equal to n+sod(n) for n = 81872197 and 81872206.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14027 + ... + 18986.

Almost surely, 2^81872240 is an apocalyptic number.

81872240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81872240 is an abundant number, since it is smaller than the sum of its proper divisors (114627088).

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

81872240 is a wasteful number, since it uses less digits than its factorization.

81872240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33057 (or 33051 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 32.

The square root of 81872240 is about 9048.3280223476. The cubic root of 81872240 is about 434.2224008249. Note that the first 3 decimals are identical.

The spelling of 81872240 in words is "eighty-one million, eight hundred seventy-two thousand, two hundred forty".