81146920 has 32 divisors (see below), whose sum is σ = 187518600. Its totient is φ = 31580928.

The previous prime is 81146909. The next prime is 81146941. The reversal of 81146920 is 2964118.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 68459076 + 12687844 = 8274^2 + 3562^2 .

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, 25935 + ... + 28894.

Almost surely, 2^81146920 is an apocalyptic number.

It is an amenable number.

81146920 is an abundant number, since it is smaller than the sum of its proper divisors (106371680).

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

81146920 is a wasteful number, since it uses less digits than its factorization.

81146920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54877 (or 54873 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 81146920 is about 9008.1585243600. The cubic root of 81146920 is about 432.9363122305.

The spelling of 81146920 in words is "eighty-one million, one hundred forty-six thousand, nine hundred twenty".