821884145617 has 4 divisors (see below), whose sum is σ = 821925489060. Its totient is φ = 821842802176.

The previous prime is 821884145507. The next prime is 821884145623. The reversal of 821884145617 is 716541488128.

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 433660443841 + 388223701776 = 658529^2 + 623076^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821884145617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821884145717) 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, 20641888 + ... + 20681665.

It is an arithmetic number, because the mean of its divisors is an integer number (205481372265).

Almost surely, 2^821884145617 is an apocalyptic number.

It is an amenable number.

821884145617 is a deficient number, since it is larger than the sum of its proper divisors (41343443).

821884145617 is a wasteful number, since it uses less digits than its factorization.

821884145617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41343442.

The product of its digits is 3440640, while the sum is 55.

The spelling of 821884145617 in words is "eight hundred twenty-one billion, eight hundred eighty-four million, one hundred forty-five thousand, six hundred seventeen".