81849091 has 2 divisors, whose sum is σ = 81849092. Its totient is φ = 81849090.

The previous prime is 81849077. The next prime is 81849149. The reversal of 81849091 is 19094818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81849091 - 2¹¹ = 81847043 is a prime.

It is not a weakly prime, because it can be changed into another prime (81849041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40924545 + 40924546.

It is an arithmetic number, because the mean of its divisors is an integer number (40924546).

Almost surely, 2^81849091 is an apocalyptic number.

81849091 is a deficient number, since it is larger than the sum of its proper divisors (1).

81849091 is an equidigital number, since it uses as much as digits as its factorization.

81849091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 40.

The square root of 81849091 is about 9047.0487453092. The cubic root of 81849091 is about 434.1814721704.

The spelling of 81849091 in words is "eighty-one million, eight hundred forty-nine thousand, ninety-one".