81707489321 has 4 divisors (see below), whose sum is σ = 81757710672. Its totient is φ = 81657267972.

The previous prime is 81707489251. The next prime is 81707489371. The reversal of 81707489321 is 12398470718.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12398470718 = 2 ⋅6199235359.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81707489321 is a prime.

It is a super-2 number, since 2×81707489321² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81707489321.

It is not an unprimeable number, because it can be changed into a prime (81707489371) 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, 25108235 + ... + 25111488.

It is an arithmetic number, because the mean of its divisors is an integer number (20439427668).

Almost surely, 2^81707489321 is an apocalyptic number.

It is an amenable number.

81707489321 is a deficient number, since it is larger than the sum of its proper divisors (50221351).

81707489321 is a wasteful number, since it uses less digits than its factorization.

81707489321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50221350.

The product of its (nonzero) digits is 677376, while the sum is 50.

The spelling of 81707489321 in words is "eighty-one billion, seven hundred seven million, four hundred eighty-nine thousand, three hundred twenty-one".