81107820 has 36 divisors (see below), whose sum is σ = 246027600. Its totient is φ = 21628704.

The previous prime is 81107801. The next prime is 81107837. The reversal of 81107820 is 2870118.

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 225120 + ... + 225479.

It is an arithmetic number, because the mean of its divisors is an integer number (6834100).

Almost surely, 2^81107820 is an apocalyptic number.

It is an amenable number.

81107820 is an abundant number, since it is smaller than the sum of its proper divisors (164919780).

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

81107820 is a wasteful number, since it uses less digits than its factorization.

81107820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450614 (or 450609 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 81107820 is about 9005.9880079867. The cubic root of 81107820 is about 432.8667654160.

Adding to 81107820 its reverse (2870118), we get a palindrome (83977938).

The spelling of 81107820 in words is "eighty-one million, one hundred seven thousand, eight hundred twenty".