81770857 has 10 divisors (see below), whose sum is σ = 95396458. Its totient is φ = 70087248.

The previous prime is 81770837. The next prime is 81770881. The reversal of 81770857 is 75807718.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 78659161 + 3111696 = 8869^2 + 1764^2 .

It is not a de Polignac number, because 81770857 - 2¹⁹ = 81246569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81770827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 14628 + ... + 19429.

Almost surely, 2^81770857 is an apocalyptic number.

It is an amenable number.

81770857 is a deficient number, since it is larger than the sum of its proper divisors (13625601).

81770857 is an frugal number, since it uses more digits than its factorization.

81770857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34085 (or 34064 counting only the distinct ones).

The product of its (nonzero) digits is 109760, while the sum is 43.

The square root of 81770857 is about 9042.7239811906. The cubic root of 81770857 is about 434.0430931889.

The spelling of 81770857 in words is "eighty-one million, seven hundred seventy thousand, eight hundred fifty-seven".