81827649 has 6 divisors (see below), whose sum is σ = 118195506. Its totient is φ = 54551760.

The previous prime is 81827639. The next prime is 81827651. The reversal of 81827649 is 94672818.

It can be written as a sum of positive squares in only one way, i.e., 78641424 + 3186225 = 8868^2 + 1785^2 .

It is not a de Polignac number, because 81827649 - 2⁸ = 81827393 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81827639) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 4545972 + ... + 4545989.

It is an arithmetic number, because the mean of its divisors is an integer number (19699251).

Almost surely, 2^81827649 is an apocalyptic number.

It is an amenable number.

81827649 is a deficient number, since it is larger than the sum of its proper divisors (36367857).

81827649 is a wasteful number, since it uses less digits than its factorization.

81827649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9091967 (or 9091964 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 81827649 is about 9045.8636403607. The cubic root of 81827649 is about 434.1435546969.

The spelling of 81827649 in words is "eighty-one million, eight hundred twenty-seven thousand, six hundred forty-nine".