823864172121 has 12 divisors (see below), whose sum is σ = 1206327753748. Its totient is φ = 541718907264.

The previous prime is 823864172099. The next prime is 823864172143. The reversal of 823864172121 is 121271468328.

823864172121 is a `hidden beast` number, since 82 + 38 + 6 + 417 + 2 + 121 = 666.

It is an interprime number because it is at equal distance from previous prime (823864172099) and next prime (823864172143).

It can be written as a sum of positive squares in 2 ways, for example, as 164844932121 + 659019240000 = 406011^2 + 811800^2 .

It is not a de Polignac number, because 823864172121 - 2⁶ = 823864172057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (823864182121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 626988820 + ... + 626990133.

Almost surely, 2^823864172121 is an apocalyptic number.

It is an amenable number.

823864172121 is a deficient number, since it is larger than the sum of its proper divisors (382463581627).

823864172121 is a wasteful number, since it uses less digits than its factorization.

823864172121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1253979032 (or 1253979029 counting only the distinct ones).

The product of its digits is 258048, while the sum is 45.

The spelling of 823864172121 in words is "eight hundred twenty-three billion, eight hundred sixty-four million, one hundred seventy-two thousand, one hundred twenty-one".