817749122978 has 6 divisors (see below), whose sum is σ = 1226625602769. Its totient is φ = 408873922056.

The previous prime is 817749122963. The next prime is 817749122987. The reversal of 817749122978 is 879221947718.

It can be written as a sum of positive squares in 2 ways, for example, as 502104039649 + 315645083329 = 708593^2 + 561823^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=639433.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 959150 + ... + 1598582.

Almost surely, 2^817749122978 is an apocalyptic number.

817749122978 is a deficient number, since it is larger than the sum of its proper divisors (408876479791).

817749122978 is an frugal number, since it uses more digits than its factorization.

817749122978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1278868 (or 639435 counting only the distinct ones).

The product of its digits is 28449792, while the sum is 65.

The spelling of 817749122978 in words is "eight hundred seventeen billion, seven hundred forty-nine million, one hundred twenty-two thousand, nine hundred seventy-eight".