81849937305491 has 2 divisors, whose sum is σ = 81849937305492. Its totient is φ = 81849937305490.

The previous prime is 81849937305481. The next prime is 81849937305541. The reversal of 81849937305491 is 19450373994818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81849937305491 - 2¹⁰ = 81849937304467 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81849937305481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40924968652745 + 40924968652746.

It is an arithmetic number, because the mean of its divisors is an integer number (40924968652746).

Almost surely, 2^{81849937305491} is an apocalyptic number.

81849937305491 is a deficient number, since it is larger than the sum of its proper divisors (1).

81849937305491 is an equidigital number, since it uses as much as digits as its factorization.

81849937305491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 235146240, while the sum is 71.

The spelling of 81849937305491 in words is "eighty-one trillion, eight hundred forty-nine billion, nine hundred thirty-seven million, three hundred five thousand, four hundred ninety-one".