817290129681 has 27 divisors (see below), whose sum is σ = 1225982755803. Its totient is φ = 544811268240.

The previous prime is 817290129671. The next prime is 817290129683. The reversal of 817290129681 is 186921092718.

It is a happy number.

The square root of 817290129681 is 904041.

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., 17624952081 + 799665177600 = 132759^2 + 894240^2 .

It is a tau number, because it is divible by the number of its divisors (27).

It is not a de Polignac number, because 817290129681 - 2⁷ = 817290129553 is a prime.

It is a super-2 number, since 2×817290129681² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (817290129683) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 73221741 + ... + 73232901.

Almost surely, 2^817290129681 is an apocalyptic number.

817290129681 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

817290129681 is the 904041-st square number.

817290129681 is the 452021-st centered octagonal number.

It is an amenable number.

817290129681 is a deficient number, since it is larger than the sum of its proper divisors (408692626122).

817290129681 is an frugal number, since it uses more digits than its factorization.

817290129681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22346 (or 11164 counting only the distinct ones).

The product of its (nonzero) digits is 870912, while the sum is 54.

The spelling of 817290129681 in words is "eight hundred seventeen billion, two hundred ninety million, one hundred twenty-nine thousand, six hundred eighty-one".