81550441 has 4 divisors (see below), whose sum is σ = 93200512. Its totient is φ = 69900372.

The previous prime is 81550409. The next prime is 81550459. The reversal of 81550441 is 14405518.

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 81550441 - 2⁵ = 81550409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81556441) 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, 5825025 + ... + 5825038.

It is an arithmetic number, because the mean of its divisors is an integer number (23300128).

Almost surely, 2^81550441 is an apocalyptic number.

It is an amenable number.

81550441 is a deficient number, since it is larger than the sum of its proper divisors (11650071).

81550441 is a wasteful number, since it uses less digits than its factorization.

81550441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11650070.

The product of its (nonzero) digits is 3200, while the sum is 28.

The square root of 81550441 is about 9030.5282791208. The cubic root of 81550441 is about 433.6527498340.

Adding to 81550441 its reverse (14405518), we get a palindrome (95955959).

The spelling of 81550441 in words is "eighty-one million, five hundred fifty thousand, four hundred forty-one".