81280299409 has 9 divisors (see below), whose sum is σ = 81917281201. Its totient is φ = 80648239360.

The previous prime is 81280299349. The next prime is 81280299467. The reversal of 81280299409 is 90499208218.

The square root of 81280299409 is 285097.

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

It can be written as a sum of positive squares in 4 ways, for example, as 96334225 + 81183965184 = 9815^2 + 284928^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81280299409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81280299109) 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, 39057249 + ... + 39059329.

Almost surely, 2^81280299409 is an apocalyptic number.

81280299409 is the 285097-th square number.

81280299409 is the 142549-th centered octagonal number.

It is an amenable number.

81280299409 is a deficient number, since it is larger than the sum of its proper divisors (636981792).

81280299409 is an frugal number, since it uses more digits than its factorization.

81280299409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4436 (or 2218 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 52.

It can be divided in two parts, 81280 and 299409, that added together give a square (380689 = 617²).

The spelling of 81280299409 in words is "eighty-one billion, two hundred eighty million, two hundred ninety-nine thousand, four hundred nine".