81304511 has 4 divisors (see below), whose sum is σ = 81944832. Its totient is φ = 80664192.

The previous prime is 81304507. The next prime is 81304541. The reversal of 81304511 is 11540318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81304511 - 2² = 81304507 is a prime.

It is a super-2 number, since 2×81304511² = 13220847017898242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81304541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 319970 + ... + 320223.

It is an arithmetic number, because the mean of its divisors is an integer number (20486208).

Almost surely, 2^81304511 is an apocalyptic number.

81304511 is a deficient number, since it is larger than the sum of its proper divisors (640321).

81304511 is a wasteful number, since it uses less digits than its factorization.

81304511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640320.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 81304511 is about 9016.9014079117. The cubic root of 81304511 is about 433.2163916527.

Adding to 81304511 its reverse (11540318), we get a palindrome (92844829).

The spelling of 81304511 in words is "eighty-one million, three hundred four thousand, five hundred eleven".