81441700261 has 4 divisors (see below), whose sum is σ = 81445721292. Its totient is φ = 81437679232.

The previous prime is 81441700213. The next prime is 81441700289. The reversal of 81441700261 is 16200714418.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 30142168225 + 51299532036 = 173615^2 + 226494^2 .

It is a cyclic number.

It is not a de Polignac number, because 81441700261 - 2²¹ = 81439603109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81441700861) 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, 1979980 + ... + 2020693.

It is an arithmetic number, because the mean of its divisors is an integer number (20361430323).

Almost surely, 2^81441700261 is an apocalyptic number.

It is an amenable number.

81441700261 is a deficient number, since it is larger than the sum of its proper divisors (4021031).

81441700261 is a wasteful number, since it uses less digits than its factorization.

81441700261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4021030.

The product of its (nonzero) digits is 10752, while the sum is 34.

The spelling of 81441700261 in words is "eighty-one billion, four hundred forty-one million, seven hundred thousand, two hundred sixty-one".