81320212 has 12 divisors (see below), whose sum is σ = 142500820. Its totient is φ = 40605696.

The previous prime is 81320189. The next prime is 81320219. The reversal of 81320212 is 21202318.

It can be written as a sum of positive squares in 2 ways, for example, as 50893956 + 30426256 = 7134^2 + 5516^2 .

It is a super-2 number, since 2×81320212² = 13225953759449888, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81320212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81320219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10143 + ... + 16294.

Almost surely, 2^81320212 is an apocalyptic number.

It is an amenable number.

81320212 is a deficient number, since it is larger than the sum of its proper divisors (61180608).

81320212 is a wasteful number, since it uses less digits than its factorization.

81320212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27210 (or 27208 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 81320212 is about 9017.7720086505. The cubic root of 81320212 is about 433.2442765047.

It can be divided in two parts, 813 and 20212, that added together give a square (21025 = 145²).

The spelling of 81320212 in words is "eighty-one million, three hundred twenty thousand, two hundred twelve".