81307389 has 16 divisors (see below), whose sum is σ = 114936320. Its totient is φ = 51036480.

The previous prime is 81307337. The next prime is 81307399. The reversal of 81307389 is 98370318.

It is not a de Polignac number, because 81307389 - 2⁹ = 81306877 is a prime.

It is a super-2 number, since 2×81307389² = 13221783011994642, which contains 22 as substring.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81307319) 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, 8374 + ... + 15255.

It is an arithmetic number, because the mean of its divisors is an integer number (7183520).

Almost surely, 2^81307389 is an apocalyptic number.

It is an amenable number.

81307389 is a deficient number, since it is larger than the sum of its proper divisors (33628931).

81307389 is a wasteful number, since it uses less digits than its factorization.

81307389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23700.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 81307389 is about 9017.0609956903. The cubic root of 81307389 is about 433.2215032267.

The spelling of 81307389 in words is "eighty-one million, three hundred seven thousand, three hundred eighty-nine".