81759820 has 12 divisors (see below), whose sum is σ = 171695664. Its totient is φ = 32703920.

The previous prime is 81759773. The next prime is 81759827. The reversal of 81759820 is 2895718.

It is not an unprimeable number, because it can be changed into a prime (81759827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2043976 + ... + 2044015.

It is an arithmetic number, because the mean of its divisors is an integer number (14307972).

Almost surely, 2^81759820 is an apocalyptic number.

It is an amenable number.

81759820 is an abundant number, since it is smaller than the sum of its proper divisors (89935844).

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

81759820 is a wasteful number, since it uses less digits than its factorization.

81759820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4088000 (or 4087998 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 81759820 is about 9042.1136909464. The cubic root of 81759820 is about 434.0235640260.

The spelling of 81759820 in words is "eighty-one million, seven hundred fifty-nine thousand, eight hundred twenty".