81000649 has 2 divisors, whose sum is σ = 81000650. Its totient is φ = 81000648.

The previous prime is 81000643. The next prime is 81000653. The reversal of 81000649 is 94600018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73410624 + 7590025 = 8568^2 + 2755^2 .

It is a cyclic number.

It is not a de Polignac number, because 81000649 - 2¹¹ = 80998601 is a prime.

It is a super-2 number, since 2×81000649² = 13122210276842402, which contains 22 as substring.

It is a Chen prime.

It is equal to p_4724452 and since 81000649 and 4724452 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81000643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40500324 + 40500325.

It is an arithmetic number, because the mean of its divisors is an integer number (40500325).

Almost surely, 2^81000649 is an apocalyptic number.

It is an amenable number.

81000649 is a deficient number, since it is larger than the sum of its proper divisors (1).

81000649 is an equidigital number, since it uses as much as digits as its factorization.

81000649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 81000649 is about 9000.0360554833. The cubic root of 81000649 is about 432.6760266693.

The spelling of 81000649 in words is "eighty-one million, six hundred forty-nine", and thus it is an aban number.