81212011 has 4 divisors (see below), whose sum is σ = 84742992. Its totient is φ = 77681032.

The previous prime is 81211987. The next prime is 81212039. The reversal of 81212011 is 11021218.

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 81212011 - 2⁷ = 81211883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81212041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1765456 + ... + 1765501.

It is an arithmetic number, because the mean of its divisors is an integer number (21185748).

Almost surely, 2^81212011 is an apocalyptic number.

81212011 is a deficient number, since it is larger than the sum of its proper divisors (3530981).

81212011 is a wasteful number, since it uses less digits than its factorization.

81212011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3530980.

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 81212011 is about 9011.7706917120. The cubic root of 81212011 is about 433.0520394655.

Adding to 81212011 its reverse (11021218), we get a palindrome (92233229).

The spelling of 81212011 in words is "eighty-one million, two hundred twelve thousand, eleven".