81546820 has 12 divisors (see below), whose sum is σ = 171248364. Its totient is φ = 32618720.

The previous prime is 81546793. The next prime is 81546821. The reversal of 81546820 is 2864518.

It can be written as a sum of positive squares in 2 ways, for example, as 26460736 + 55086084 = 5144^2 + 7422^2 .

It is a super-2 number, since 2×81546820² = 13299767704224800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81546821) 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, 2038651 + ... + 2038690.

It is an arithmetic number, because the mean of its divisors is an integer number (14270697).

Almost surely, 2^81546820 is an apocalyptic number.

It is an amenable number.

81546820 is an abundant number, since it is smaller than the sum of its proper divisors (89701544).

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

81546820 is a wasteful number, since it uses less digits than its factorization.

81546820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4077350 (or 4077348 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 34.

The square root of 81546820 is about 9030.3277902854. The cubic root of 81546820 is about 433.6463313940.

The spelling of 81546820 in words is "eighty-one million, five hundred forty-six thousand, eight hundred twenty".