81864767869 has 4 divisors (see below), whose sum is σ = 83086630144. Its totient is φ = 80642905596.

The previous prime is 81864767839. The next prime is 81864767891. The reversal of 81864767869 is 96876746818.

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.

It is a cyclic number.

It is not a de Polignac number, because 81864767869 - 2²¹ = 81862670717 is a prime.

It is a super-2 number, since 2×81864767869² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81864767798 and 81864767807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81864767839) 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, 610931037 + ... + 610931170.

It is an arithmetic number, because the mean of its divisors is an integer number (20771657536).

Almost surely, 2^81864767869 is an apocalyptic number.

It is an amenable number.

81864767869 is a deficient number, since it is larger than the sum of its proper divisors (1221862275).

81864767869 is a wasteful number, since it uses less digits than its factorization.

81864767869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1221862274.

The product of its digits is 195084288, while the sum is 70.

The spelling of 81864767869 in words is "eighty-one billion, eight hundred sixty-four million, seven hundred sixty-seven thousand, eight hundred sixty-nine".