81634081 has 4 divisors (see below), whose sum is σ = 83532592. Its totient is φ = 79735572.

The previous prime is 81634057. The next prime is 81634121. The reversal of 81634081 is 18043618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81634081 - 2⁷ = 81633953 is a prime.

It is a super-2 number, since 2×81634081² = 13328246361429122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81634031) 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 3 ways as a sum of consecutive naturals, for example, 949191 + ... + 949276.

It is an arithmetic number, because the mean of its divisors is an integer number (20883148).

Almost surely, 2^81634081 is an apocalyptic number.

It is an amenable number.

81634081 is a deficient number, since it is larger than the sum of its proper divisors (1898511).

81634081 is a wasteful number, since it uses less digits than its factorization.

81634081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1898510.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 81634081 is about 9035.1580506375. The cubic root of 81634081 is about 433.8009539091.

Adding to 81634081 its reverse (18043618), we get a palindrome (99677699).

It can be divided in two parts, 8163 and 4081, that multiplied together give a triangular number (33313203 = T₈₁₆₂).

The spelling of 81634081 in words is "eighty-one million, six hundred thirty-four thousand, eighty-one".