81548209 has 4 divisors (see below), whose sum is σ = 85840240. Its totient is φ = 77256180.

The previous prime is 81548183. The next prime is 81548219. The reversal of 81548209 is 90284518.

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 81548209 - 2⁵ = 81548177 is a prime.

It is a super-2 number, since 2×81548209² = 13300220782215362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81548219) 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, 2145987 + ... + 2146024.

It is an arithmetic number, because the mean of its divisors is an integer number (21460060).

Almost surely, 2^81548209 is an apocalyptic number.

It is an amenable number.

81548209 is a deficient number, since it is larger than the sum of its proper divisors (4292031).

81548209 is a wasteful number, since it uses less digits than its factorization.

81548209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4292030.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 81548209 is about 9030.4046974651. The cubic root of 81548209 is about 433.6487935024.

The spelling of 81548209 in words is "eighty-one million, five hundred forty-eight thousand, two hundred nine".