81353791 has 2 divisors, whose sum is σ = 81353792. Its totient is φ = 81353790.

The previous prime is 81353777. The next prime is 81353819. The reversal of 81353791 is 19735318.

81353791 = T₇₃₆₃ + T₇₃₆₄ + T₇₃₆₅.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81353791 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81353791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81353731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40676895 + 40676896.

It is an arithmetic number, because the mean of its divisors is an integer number (40676896).

Almost surely, 2^81353791 is an apocalyptic number.

81353791 is the 7365-th centered triangular number.

81353791 is a deficient number, since it is larger than the sum of its proper divisors (1).

81353791 is an equidigital number, since it uses as much as digits as its factorization.

81353791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 37.

The square root of 81353791 is about 9019.6336400100. The cubic root of 81353791 is about 433.3039004993.

The spelling of 81353791 in words is "eighty-one million, three hundred fifty-three thousand, seven hundred ninety-one".