81078920 has 32 divisors (see below), whose sum is σ = 196461720. Its totient is φ = 29936640.

The previous prime is 81078917. The next prime is 81078953. The reversal of 81078920 is 2987018.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 48748324 + 32330596 = 6982^2 + 5686^2 .

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, 77441 + ... + 78480.

Almost surely, 2^81078920 is an apocalyptic number.

It is an amenable number.

81078920 is an abundant number, since it is smaller than the sum of its proper divisors (115382800).

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

81078920 is a wasteful number, since it uses less digits than its factorization.

81078920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155945 (or 155941 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 81078920 is about 9004.3833770003. The cubic root of 81078920 is about 432.8153468818.

The spelling of 81078920 in words is "eighty-one million, seventy-eight thousand, nine hundred twenty".