81870001 has 8 divisors (see below), whose sum is σ = 83906280. Its totient is φ = 79852032.

The previous prime is 81869981. The next prime is 81870013. The reversal of 81870001 is 10007818.

It can be written as a sum of positive squares in 4 ways, for example, as 15610401 + 66259600 = 3951^2 + 8140^2 .

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 81870001 - 2¹¹ = 81867953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81870091) 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, 4705 + ... + 13633.

It is an arithmetic number, because the mean of its divisors is an integer number (10488285).

Almost surely, 2^81870001 is an apocalyptic number.

It is an amenable number.

81870001 is a deficient number, since it is larger than the sum of its proper divisors (2036279).

81870001 is a wasteful number, since it uses less digits than its factorization.

81870001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9155.

The product of its (nonzero) digits is 448, while the sum is 25.

The square root of 81870001 is about 9048.2042969862. The cubic root of 81870001 is about 434.2184424917.

Adding to 81870001 its reverse (10007818), we get a palindrome (91877819).

The spelling of 81870001 in words is "eighty-one million, eight hundred seventy thousand, one".