81530409 has 4 divisors (see below), whose sum is σ = 108707216. Its totient is φ = 54353604.

The previous prime is 81530381. The next prime is 81530413. The reversal of 81530409 is 90403518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81530409 - 2²⁰ = 80481833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81530459) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13588399 + ... + 13588404.

It is an arithmetic number, because the mean of its divisors is an integer number (27176804).

Almost surely, 2^81530409 is an apocalyptic number.

It is an amenable number.

81530409 is a deficient number, since it is larger than the sum of its proper divisors (27176807).

81530409 is a wasteful number, since it uses less digits than its factorization.

81530409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27176806.

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 81530409 is about 9029.4190843044. The cubic root of 81530409 is about 433.6172395284.

The spelling of 81530409 in words is "eighty-one million, five hundred thirty thousand, four hundred nine".