81213030441 has 9 divisors (see below), whose sum is σ = 117308945559. Its totient is φ = 54141450336.

The previous prime is 81213030421. The next prime is 81213030517. The reversal of 81213030441 is 14403031218.

The square root of 81213030441 is 284979.

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

81213030441 is a `hidden beast` number, since 8 + 1 + 213 + 0 + 3 + 0 + 441 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7063562025 + 74149468416 = 84045^2 + 272304^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 81213030441 - 2³¹ = 79065546793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81213030421) 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, 807441 + ... + 902433.

Almost surely, 2^81213030441 is an apocalyptic number.

81213030441 is the 284979-th square number.

81213030441 is the 142490-th centered octagonal number.

It is an amenable number.

81213030441 is a deficient number, since it is larger than the sum of its proper divisors (36095915118).

81213030441 is an frugal number, since it uses more digits than its factorization.

81213030441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189992 (or 94996 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

Multiplying 81213030441 by its product of nonzero digits (2304), we get a square (187114822136064 = 13678992²).

Adding to 81213030441 its reverse (14403031218), we get a palindrome (95616061659).

The spelling of 81213030441 in words is "eighty-one billion, two hundred thirteen million, thirty thousand, four hundred forty-one".