81097859749 has 2 divisors, whose sum is σ = 81097859750. Its totient is φ = 81097859748.

The previous prime is 81097859743. The next prime is 81097859753. The reversal of 81097859749 is 94795879018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60957141025 + 20140718724 = 246895^2 + 141918^2 .

It is a cyclic number.

It is not a de Polignac number, because 81097859749 - 2¹⁵ = 81097826981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81097859743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40548929874 + 40548929875.

It is an arithmetic number, because the mean of its divisors is an integer number (40548929875).

Almost surely, 2^81097859749 is an apocalyptic number.

It is an amenable number.

81097859749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81097859749 is an equidigital number, since it uses as much as digits as its factorization.

81097859749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45722880, while the sum is 67.

The spelling of 81097859749 in words is "eighty-one billion, ninety-seven million, eight hundred fifty-nine thousand, seven hundred forty-nine".