81990367 has 2 divisors, whose sum is σ = 81990368. Its totient is φ = 81990366.

The previous prime is 81990361. The next prime is 81990373. The reversal of 81990367 is 76309918.

It is a balanced prime because it is at equal distance from previous prime (81990361) and next prime (81990373).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81990367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81990361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40995183 + 40995184.

It is an arithmetic number, because the mean of its divisors is an integer number (40995184).

Almost surely, 2^81990367 is an apocalyptic number.

81990367 is a deficient number, since it is larger than the sum of its proper divisors (1).

81990367 is an equidigital number, since it uses as much as digits as its factorization.

81990367 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 43.

The square root of 81990367 is about 9054.8532290700. The cubic root of 81990367 is about 434.4311355569.

The spelling of 81990367 in words is "eighty-one million, nine hundred ninety thousand, three hundred sixty-seven".