81226661 has 4 divisors (see below), whose sum is σ = 81244800. Its totient is φ = 81208524.

The previous prime is 81226637. The next prime is 81226667. The reversal of 81226661 is 16662218.

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 81226661 - 2¹⁸ = 80964517 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81226667) 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, 3020 + ... + 13098.

It is an arithmetic number, because the mean of its divisors is an integer number (20311200).

Almost surely, 2^81226661 is an apocalyptic number.

It is an amenable number.

81226661 is a deficient number, since it is larger than the sum of its proper divisors (18139).

81226661 is a wasteful number, since it uses less digits than its factorization.

81226661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18138.

The product of its digits is 6912, while the sum is 32.

The square root of 81226661 is about 9012.5834808894. The cubic root of 81226661 is about 433.0780776129.

Adding to 81226661 its reverse (16662218), we get a palindrome (97888879).

The spelling of 81226661 in words is "eighty-one million, two hundred twenty-six thousand, six hundred sixty-one".