81306289 has 9 divisors (see below), whose sum is σ = 83122041. Its totient is φ = 79529940.

The previous prime is 81306271. The next prime is 81306299. The reversal of 81306289 is 98260318.

The square root of 81306289 is 9017.

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

It is not a de Polignac number, because 81306289 - 2²³ = 72917681 is a prime.

It is a super-2 number, since 2×81306289² = 13221425261903042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81306259) 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, 640144 + ... + 640270.

Almost surely, 2^81306289 is an apocalyptic number.

81306289 is the 9017-th square number.

81306289 is the 4509-th centered octagonal number.

It is an amenable number.

81306289 is a deficient number, since it is larger than the sum of its proper divisors (1815752).

81306289 is an frugal number, since it uses more digits than its factorization.

81306289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 396 (or 198 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 37.

The cubic root of 81306289 is about 433.2195495469.

Multiplying 81306289 by its product of nonzero digits (20736), we get a square (1685967208704 = 1298448²).

The spelling of 81306289 in words is "eighty-one million, three hundred six thousand, two hundred eighty-nine".