81905741 has 4 divisors (see below), whose sum is σ = 83903484. Its totient is φ = 79908000.

The previous prime is 81905731. The next prime is 81905771. The reversal of 81905741 is 14750918.

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 5080516 + 76825225 = 2254^2 + 8765^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81905741 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 (81905731) 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, 998810 + ... + 998891.

It is an arithmetic number, because the mean of its divisors is an integer number (20975871).

Almost surely, 2^81905741 is an apocalyptic number.

It is an amenable number.

81905741 is a deficient number, since it is larger than the sum of its proper divisors (1997743).

81905741 is a wasteful number, since it uses less digits than its factorization.

81905741 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1997742.

The product of its (nonzero) digits is 10080, while the sum is 35.

The square root of 81905741 is about 9050.1790590021. The cubic root of 81905741 is about 434.2816187029.

It can be divided in two parts, 8190 and 5741, that added together give a palindrome (13931).

The spelling of 81905741 in words is "eighty-one million, nine hundred five thousand, seven hundred forty-one".