81488909 has 4 divisors (see below), whose sum is σ = 81520416. Its totient is φ = 81457404.

The previous prime is 81488893. The next prime is 81488941. The reversal of 81488909 is 90988418.

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 a cyclic number.

It is not a de Polignac number, because 81488909 - 2⁴ = 81488893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81488969) 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, 11489 + ... + 17174.

It is an arithmetic number, because the mean of its divisors is an integer number (20380104).

Almost surely, 2^81488909 is an apocalyptic number.

It is an amenable number.

81488909 is a deficient number, since it is larger than the sum of its proper divisors (31507).

81488909 is a wasteful number, since it uses less digits than its factorization.

81488909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31506.

The product of its (nonzero) digits is 165888, while the sum is 47.

The square root of 81488909 is about 9027.1207480569. The cubic root of 81488909 is about 433.5436548386.

The spelling of 81488909 in words is "eighty-one million, four hundred eighty-eight thousand, nine hundred nine".