81726802641 has 27 divisors (see below), whose sum is σ = 129772226857. Its totient is φ = 49525677960.

The previous prime is 81726802529. The next prime is 81726802657. The reversal of 81726802641 is 14620862718.

The square root of 81726802641 is 285879.

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

It is not a de Polignac number, because 81726802641 - 2¹⁷ = 81726671569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81726802441) 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, 9429676 + ... + 9438338.

Almost surely, 2^81726802641 is an apocalyptic number.

81726802641 is the 285879-th square number.

81726802641 is the 142940-th centered octagonal number.

It is an amenable number.

81726802641 is a deficient number, since it is larger than the sum of its proper divisors (48045424216).

81726802641 is an frugal number, since it uses more digits than its factorization.

81726802641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17354 (or 8677 counting only the distinct ones).

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

The spelling of 81726802641 in words is "eighty-one billion, seven hundred twenty-six million, eight hundred two thousand, six hundred forty-one".