81213489 has 16 divisors (see below), whose sum is σ = 137504640. Its totient is φ = 46407600.

The previous prime is 81213443. The next prime is 81213491. The reversal of 81213489 is 98431218.

It is not a de Polignac number, because 81213489 - 2²¹ = 79116337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81213289) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 214662 + ... + 215039.

It is an arithmetic number, because the mean of its divisors is an integer number (8594040).

Almost surely, 2^81213489 is an apocalyptic number.

It is an amenable number.

81213489 is a deficient number, since it is larger than the sum of its proper divisors (56291151).

81213489 is a wasteful number, since it uses less digits than its factorization.

81213489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429717 (or 429711 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 81213489 is about 9011.8526952009. The cubic root of 81213489 is about 433.0546665278.

The spelling of 81213489 in words is "eighty-one million, two hundred thirteen thousand, four hundred eighty-nine".