81402217 has 8 divisors (see below), whose sum is σ = 90687240. Its totient is φ = 72549120.

The previous prime is 81402203. The next prime is 81402229. The reversal of 81402217 is 71220418.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 22127616 + 59274601 = 4704^2 + 7699^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81402217 - 2⁷ = 81402089 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81402191 and 81402200.

It is not an unprimeable number, because it can be changed into a prime (81402247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 107584 + ... + 108337.

It is an arithmetic number, because the mean of its divisors is an integer number (11335905).

Almost surely, 2^81402217 is an apocalyptic number.

It is an amenable number.

81402217 is a deficient number, since it is larger than the sum of its proper divisors (9285023).

81402217 is a wasteful number, since it uses less digits than its factorization.

81402217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215963.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 81402217 is about 9022.3177177486. The cubic root of 81402217 is about 433.3898584384.

The spelling of 81402217 in words is "eighty-one million, four hundred two thousand, two hundred seventeen".