81851228 has 12 divisors (see below), whose sum is σ = 143327352. Its totient is φ = 40900560.

The previous prime is 81851207. The next prime is 81851233. The reversal of 81851228 is 82215818.

It is a super-3 number, since 3×81851228³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2426 + ... + 13022.

It is an arithmetic number, because the mean of its divisors is an integer number (11943946).

Almost surely, 2^81851228 is an apocalyptic number.

It is an amenable number.

81851228 is a deficient number, since it is larger than the sum of its proper divisors (61476124).

81851228 is a wasteful number, since it uses less digits than its factorization.

81851228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12532 (or 12530 counting only the distinct ones).

The product of its digits is 10240, while the sum is 35.

The square root of 81851228 is about 9047.1668493512. The cubic root of 81851228 is about 434.1852508225.

The spelling of 81851228 in words is "eighty-one million, eight hundred fifty-one thousand, two hundred twenty-eight".