84531721765 has 4 divisors (see below), whose sum is σ = 101438066124. Its totient is φ = 67625377408.

The previous prime is 84531721759. The next prime is 84531721783. The reversal of 84531721765 is 56712713548.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17478690849 + 67053030916 = 132207^2 + 258946^2 .

It is a cyclic number.

It is not a de Polignac number, because 84531721765 - 2¹³ = 84531713573 is a prime.

It is a super-2 number, since 2×84531721765² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (49) 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 an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8453172172 + ... + 8453172181.

It is an arithmetic number, because the mean of its divisors is an integer number (25359516531).

Almost surely, 2^84531721765 is an apocalyptic number.

It is an amenable number.

84531721765 is a deficient number, since it is larger than the sum of its proper divisors (16906344359).

84531721765 is a wasteful number, since it uses less digits than its factorization.

84531721765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16906344358.

The product of its digits is 1411200, while the sum is 49.

The spelling of 84531721765 in words is "eighty-four billion, five hundred thirty-one million, seven hundred twenty-one thousand, seven hundred sixty-five".