81821367 has 16 divisors (see below), whose sum is σ = 121370080. Its totient is φ = 54478656.

The previous prime is 81821359. The next prime is 81821371. The reversal of 81821367 is 76312818.

It is not a de Polignac number, because 81821367 - 2³ = 81821359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81821387) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28803 + ... + 31515.

It is an arithmetic number, because the mean of its divisors is an integer number (7585630).

Almost surely, 2^81821367 is an apocalyptic number.

81821367 is a deficient number, since it is larger than the sum of its proper divisors (39548713).

81821367 is a wasteful number, since it uses less digits than its factorization.

81821367 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3839 (or 3833 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 81821367 is about 9045.5164031690. The cubic root of 81821367 is about 434.1324445174.

The spelling of 81821367 in words is "eighty-one million, eight hundred twenty-one thousand, three hundred sixty-seven".