82171820477 has 4 divisors (see below), whose sum is σ = 82192953660. Its totient is φ = 82150687296.

The previous prime is 82171820447. The next prime is 82171820491. The reversal of 82171820477 is 77402817128.

It is a happy number.

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 62953820836 + 19217999641 = 250906^2 + 138629^2 .

It is a cyclic number.

It is not a de Polignac number, because 82171820477 - 2⁶ = 82171820413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (82171820447) 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, 10560758 + ... + 10568535.

It is an arithmetic number, because the mean of its divisors is an integer number (20548238415).

Almost surely, 2^82171820477 is an apocalyptic number.

It is an amenable number.

82171820477 is a deficient number, since it is larger than the sum of its proper divisors (21133183).

82171820477 is a wasteful number, since it uses less digits than its factorization.

82171820477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21133182.

The product of its (nonzero) digits is 351232, while the sum is 47.

The spelling of 82171820477 in words is "eighty-two billion, one hundred seventy-one million, eight hundred twenty thousand, four hundred seventy-seven".