81549733 has 2 divisors, whose sum is σ = 81549734. Its totient is φ = 81549732.

The previous prime is 81549703. The next prime is 81549737. The reversal of 81549733 is 33794518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80874049 + 675684 = 8993^2 + 822^2 .

It is a cyclic number.

It is not a de Polignac number, because 81549733 - 2⁵ = 81549701 is a prime.

It is equal to p_4754695 and since 81549733 and 4754695 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81549737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40774866 + 40774867.

It is an arithmetic number, because the mean of its divisors is an integer number (40774867).

Almost surely, 2^81549733 is an apocalyptic number.

It is an amenable number.

81549733 is a deficient number, since it is larger than the sum of its proper divisors (1).

81549733 is an equidigital number, since it uses as much as digits as its factorization.

81549733 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 40.

The square root of 81549733 is about 9030.4890786712. The cubic root of 81549733 is about 433.6514948765.

The spelling of 81549733 in words is "eighty-one million, five hundred forty-nine thousand, seven hundred thirty-three".