85181221 has 4 divisors (see below), whose sum is σ = 85673772. Its totient is φ = 84688672.

The previous prime is 85181219. The next prime is 85181251. The reversal of 85181221 is 12218158.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46430596 + 38750625 = 6814^2 + 6225^2 .

It is a cyclic number.

It is not a de Polignac number, because 85181221 - 2¹ = 85181219 is a prime.

It is a super-2 number, since 2×85181221² = 14511680822101682, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 85181221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85181251) 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, 246016 + ... + 246361.

It is an arithmetic number, because the mean of its divisors is an integer number (21418443).

Almost surely, 2^85181221 is an apocalyptic number.

It is an amenable number.

85181221 is a deficient number, since it is larger than the sum of its proper divisors (492551).

85181221 is a wasteful number, since it uses less digits than its factorization.

85181221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 492550.

The product of its digits is 1280, while the sum is 28.

The square root of 85181221 is about 9229.3673130936. The cubic root of 85181221 is about 439.9952151684.

Adding to 85181221 its reverse (12218158), we get a palindrome (97399379).

The spelling of 85181221 in words is "eighty-five million, one hundred eighty-one thousand, two hundred twenty-one".