81770205 has 32 divisors (see below), whose sum is σ = 150243840. Its totient is φ = 37558080.

The previous prime is 81770201. The next prime is 81770233. The reversal of 81770205 is 50207718.

It is a happy number.

It is not a de Polignac number, because 81770205 - 2² = 81770201 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81770201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9907 + ... + 16176.

It is an arithmetic number, because the mean of its divisors is an integer number (4695120).

Almost surely, 2^81770205 is an apocalyptic number.

It is an amenable number.

81770205 is a deficient number, since it is larger than the sum of its proper divisors (68473635).

81770205 is a wasteful number, since it uses less digits than its factorization.

81770205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26121.

The product of its (nonzero) digits is 3920, while the sum is 30.

The square root of 81770205 is about 9042.6879300350. The cubic root of 81770205 is about 434.0419395715.

The spelling of 81770205 in words is "eighty-one million, seven hundred seventy thousand, two hundred five".