81308811609 has 63 divisors (see below), whose sum is σ = 124705355173. Its totient is φ = 52989437304.

The previous prime is 81308811599. The next prime is 81308811611. The reversal of 81308811609 is 90611880318.

The square root of 81308811609 is 285147.

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

81308811609 is a `hidden beast` number, since 8 + 1 + 30 + 8 + 8 + 1 + 1 + 609 = 666.

It is not a de Polignac number, because 81308811609 - 2¹³ = 81308803417 is a prime.

It is a super-2 number, since 2×81308811609² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81308831609) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 454239082 + ... + 454239260.

Almost surely, 2^81308811609 is an apocalyptic number.

81308811609 is the 285147-th square number.

81308811609 is the 142574-th centered octagonal number.

It is an amenable number.

81308811609 is a deficient number, since it is larger than the sum of its proper divisors (43396543564).

81308811609 is an frugal number, since it uses more digits than its factorization.

81308811609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 494 (or 241 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The spelling of 81308811609 in words is "eighty-one billion, three hundred eight million, eight hundred eleven thousand, six hundred nine".