81381197 has 2 divisors, whose sum is σ = 81381198. Its totient is φ = 81381196.

The previous prime is 81381073. The next prime is 81381211. The reversal of 81381197 is 79118318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45549001 + 35832196 = 6749^2 + 5986^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81381197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81381197.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81381497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40690598 + 40690599.

It is an arithmetic number, because the mean of its divisors is an integer number (40690599).

Almost surely, 2^81381197 is an apocalyptic number.

It is an amenable number.

81381197 is a deficient number, since it is larger than the sum of its proper divisors (1).

81381197 is an equidigital number, since it uses as much as digits as its factorization.

81381197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 38.

The square root of 81381197 is about 9021.1527533902. The cubic root of 81381197 is about 433.3525513502.

The spelling of 81381197 in words is "eighty-one million, three hundred eighty-one thousand, one hundred ninety-seven".