81286628 has 6 divisors (see below), whose sum is σ = 142251606. Its totient is φ = 40643312.

The previous prime is 81286627. The next prime is 81286643. The reversal of 81286628 is 82668218.

It can be written as a sum of positive squares in only one way, i.e., 80964004 + 322624 = 8998^2 + 568^2 .

It is a super-2 number, since 2×81286628² = 13215031783220768, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81286627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10160825 + ... + 10160832.

It is an arithmetic number, because the mean of its divisors is an integer number (23708601).

Almost surely, 2^81286628 is an apocalyptic number.

It is an amenable number.

81286628 is a deficient number, since it is larger than the sum of its proper divisors (60964978).

81286628 is a wasteful number, since it uses less digits than its factorization.

81286628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20321661 (or 20321659 counting only the distinct ones).

The product of its digits is 73728, while the sum is 41.

The square root of 81286628 is about 9015.9097156083. The cubic root of 81286628 is about 433.1846272127.

The spelling of 81286628 in words is "eighty-one million, two hundred eighty-six thousand, six hundred twenty-eight".