82787172021 has 6 divisors (see below), whose sum is σ = 119581470710. Its totient is φ = 55191448008.

The previous prime is 82787172019. The next prime is 82787172031. The reversal of 82787172021 is 12027178728.

It can be written as a sum of positive squares in only one way, i.e., 51071480100 + 31715691921 = 225990^2 + 178089^2 .

It is not a de Polignac number, because 82787172021 - 2¹ = 82787172019 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (82787172031) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4599287326 + ... + 4599287343.

Almost surely, 2^82787172021 is an apocalyptic number.

It is an amenable number.

82787172021 is a deficient number, since it is larger than the sum of its proper divisors (36794298689).

82787172021 is a wasteful number, since it uses less digits than its factorization.

82787172021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9198574675 (or 9198574672 counting only the distinct ones).

The product of its (nonzero) digits is 175616, while the sum is 45.

The spelling of 82787172021 in words is "eighty-two billion, seven hundred eighty-seven million, one hundred seventy-two thousand, twenty-one".