228156021 has 80 divisors (see below), whose sum is σ = 380540160. Its totient is φ = 135717120.

The previous prime is 228156013. The next prime is 228156037. The reversal of 228156021 is 120651822.

It is a happy number.

228156021 is a `hidden beast` number, since 2 + 2 + 81 + 560 + 21 = 666.

It is not a de Polignac number, because 228156021 - 2³ = 228156013 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (228156041) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 2215056 + ... + 2215158.

It is an arithmetic number, because the mean of its divisors is an integer number (4756752).

Almost surely, 2^228156021 is an apocalyptic number.

It is an amenable number.

228156021 is a deficient number, since it is larger than the sum of its proper divisors (152384139).

228156021 is a wasteful number, since it uses less digits than its factorization.

228156021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 228156021 is about 15104.8343585754. The cubic root of 228156021 is about 611.0507920985.

The spelling of 228156021 in words is "two hundred twenty-eight million, one hundred fifty-six thousand, twenty-one".