81475221 has 16 divisors (see below), whose sum is σ = 112331648. Its totient is φ = 52488000.

The previous prime is 81475217. The next prime is 81475243. The reversal of 81475221 is 12257418.

It is not a de Polignac number, because 81475221 - 2² = 81475217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81475201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14331 + ... + 19191.

It is an arithmetic number, because the mean of its divisors is an integer number (7020728).

Almost surely, 2^81475221 is an apocalyptic number.

It is an amenable number.

81475221 is a deficient number, since it is larger than the sum of its proper divisors (30856427).

81475221 is a wasteful number, since it uses less digits than its factorization.

81475221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5052.

The product of its digits is 4480, while the sum is 30.

The square root of 81475221 is about 9026.3625564233. The cubic root of 81475221 is about 433.5193788240.

The spelling of 81475221 in words is "eighty-one million, four hundred seventy-five thousand, two hundred twenty-one".