81279173 has 2 divisors, whose sum is σ = 81279174. Its totient is φ = 81279172.

The previous prime is 81279151. The next prime is 81279197. The reversal of 81279173 is 37197218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70930084 + 10349089 = 8422^2 + 3217^2 .

It is a cyclic number.

It is not a de Polignac number, because 81279173 - 2¹⁴ = 81262789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81279103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40639586 + 40639587.

It is an arithmetic number, because the mean of its divisors is an integer number (40639587).

Almost surely, 2^81279173 is an apocalyptic number.

It is an amenable number.

81279173 is a deficient number, since it is larger than the sum of its proper divisors (1).

81279173 is an equidigital number, since it uses as much as digits as its factorization.

81279173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21168, while the sum is 38.

The square root of 81279173 is about 9015.4962703115. The cubic root of 81279173 is about 433.1713839925.

The spelling of 81279173 in words is "eighty-one million, two hundred seventy-nine thousand, one hundred seventy-three".