81361193 has 2 divisors, whose sum is σ = 81361194. Its totient is φ = 81361192.

The previous prime is 81361169. The next prime is 81361213. The reversal of 81361193 is 39116318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78357904 + 3003289 = 8852^2 + 1733^2 .

It is a cyclic number.

It is not a de Polignac number, because 81361193 - 2¹⁶ = 81295657 is a prime.

It is equal to p_4744328 and since 81361193 and 4744328 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81361123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40680596 + 40680597.

It is an arithmetic number, because the mean of its divisors is an integer number (40680597).

Almost surely, 2^81361193 is an apocalyptic number.

It is an amenable number.

81361193 is a deficient number, since it is larger than the sum of its proper divisors (1).

81361193 is an equidigital number, since it uses as much as digits as its factorization.

81361193 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 32.

The square root of 81361193 is about 9020.0439577643. The cubic root of 81361193 is about 433.3170415308.

The spelling of 81361193 in words is "eighty-one million, three hundred sixty-one thousand, one hundred ninety-three".