81315211 has 6 divisors (see below), whose sum is σ = 82449780. Its totient is φ = 80196048.

The previous prime is 81315191. The next prime is 81315229. The reversal of 81315211 is 11251318.

It is not a de Polignac number, because 81315211 - 2⁷ = 81315083 is a prime.

It is a super-2 number, since 2×81315211² = 13224327079949042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81315251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2301 + ... + 12958.

It is an arithmetic number, because the mean of its divisors is an integer number (13741630).

Almost surely, 2^81315211 is an apocalyptic number.

81315211 is a deficient number, since it is larger than the sum of its proper divisors (1134569).

81315211 is an equidigital number, since it uses as much as digits as its factorization.

81315211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15405 (or 15332 counting only the distinct ones).

The product of its digits is 240, while the sum is 22.

The square root of 81315211 is about 9017.4947186012. The cubic root of 81315211 is about 433.2353951578.

Adding to 81315211 its reverse (11251318), we get a palindrome (92566529).

The spelling of 81315211 in words is "eighty-one million, three hundred fifteen thousand, two hundred eleven".