81220611 has 32 divisors (see below), whose sum is σ = 122342400. Its totient is φ = 47623680.

The previous prime is 81220609. The next prime is 81220627. The reversal of 81220611 is 11602218.

It is not a de Polignac number, because 81220611 - 2¹ = 81220609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81220681) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 76021 + ... + 77081.

It is an arithmetic number, because the mean of its divisors is an integer number (3823200).

Almost surely, 2^81220611 is an apocalyptic number.

81220611 is a deficient number, since it is larger than the sum of its proper divisors (41121789).

81220611 is a wasteful number, since it uses less digits than its factorization.

81220611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1179.

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 81220611 is about 9012.2478328106. The cubic root of 81220611 is about 433.0673250373.

Adding to 81220611 its reverse (11602218), we get a palindrome (92822829).

The spelling of 81220611 in words is "eighty-one million, two hundred twenty thousand, six hundred eleven".