818719138561 has 9 divisors (see below), whose sum is σ = 820866483331. Its totient is φ = 816577403584.

The previous prime is 818719138547. The next prime is 818719138579. The reversal of 818719138561 is 165831917818.

The square root of 818719138561 is 904831.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 394345064961 + 424374073600 = 627969^2 + 651440^2 .

It is not a de Polignac number, because 818719138561 - 2¹⁵ = 818719105793 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 818719138496 and 818719138505.

It is not an unprimeable number, because it can be changed into a prime (818719130561) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 433413105 + ... + 433414993.

Almost surely, 2^818719138561 is an apocalyptic number.

818719138561 is the 904831-st square number.

818719138561 is the 452416-th centered octagonal number.

It is an amenable number.

818719138561 is a deficient number, since it is larger than the sum of its proper divisors (2147344770).

818719138561 is an frugal number, since it uses more digits than its factorization.

818719138561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4736 (or 2368 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 58.

The spelling of 818719138561 in words is "eight hundred eighteen billion, seven hundred nineteen million, one hundred thirty-eight thousand, five hundred sixty-one".