81320670 has 24 divisors (see below), whose sum is σ = 211433976. Its totient is φ = 21685488.

The previous prime is 81320653. The next prime is 81320677. The reversal of 81320670 is 7602318.

It is a super-3 number, since 3×81320670³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81320677) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 451692 + ... + 451871.

It is an arithmetic number, because the mean of its divisors is an integer number (8809749).

Almost surely, 2^81320670 is an apocalyptic number.

81320670 is an abundant number, since it is smaller than the sum of its proper divisors (130113306).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81320670 is a wasteful number, since it uses less digits than its factorization.

81320670 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 903576 (or 903573 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 81320670 is about 9017.7974029139. The cubic root of 81320670 is about 433.2450898552.

Adding to 81320670 its reverse (7602318), we get a palindrome (88922988).

The spelling of 81320670 in words is "eighty-one million, three hundred twenty thousand, six hundred seventy".