81652209 has 4 divisors (see below), whose sum is σ = 108869616. Its totient is φ = 54434804.

The previous prime is 81652189. The next prime is 81652217. The reversal of 81652209 is 90225618.

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 81652209 - 2⁸ = 81651953 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81652209.

It is not an unprimeable number, because it can be changed into a prime (81652409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13608699 + ... + 13608704.

It is an arithmetic number, because the mean of its divisors is an integer number (27217404).

Almost surely, 2^81652209 is an apocalyptic number.

It is an amenable number.

81652209 is a deficient number, since it is larger than the sum of its proper divisors (27217407).

81652209 is a wasteful number, since it uses less digits than its factorization.

81652209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27217406.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 81652209 is about 9036.1611871414. The cubic root of 81652209 is about 433.8330620742.

The spelling of 81652209 in words is "eighty-one million, six hundred fifty-two thousand, two hundred nine".