81670201 has 4 divisors (see below), whose sum is σ = 83569552. Its totient is φ = 79770852.

The previous prime is 81670187. The next prime is 81670207. The reversal of 81670201 is 10207618.

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 81670201 - 2⁹ = 81669689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81670207) 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 3 ways as a sum of consecutive naturals, for example, 949611 + ... + 949696.

It is an arithmetic number, because the mean of its divisors is an integer number (20892388).

Almost surely, 2^81670201 is an apocalyptic number.

It is an amenable number.

81670201 is a deficient number, since it is larger than the sum of its proper divisors (1899351).

81670201 is a wasteful number, since it uses less digits than its factorization.

81670201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1899350.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 81670201 is about 9037.1566878084. The cubic root of 81670201 is about 433.8649246587.

Adding to 81670201 its reverse (10207618), we get a palindrome (91877819).

It can be divided in two parts, 816 and 70201, that added together give a palindrome (71017).

The spelling of 81670201 in words is "eighty-one million, six hundred seventy thousand, two hundred one".