228291991 has 4 divisors (see below), whose sum is σ = 228446800. Its totient is φ = 228137184.

The previous prime is 228291971. The next prime is 228292007. The reversal of 228291991 is 199192822.

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

It is a cyclic number.

It is not a de Polignac number, because 228291991 - 2¹³ = 228283799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (228291901) 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, 75171 + ... + 78148.

It is an arithmetic number, because the mean of its divisors is an integer number (57111700).

Almost surely, 2^228291991 is an apocalyptic number.

228291991 is a deficient number, since it is larger than the sum of its proper divisors (154809).

228291991 is a wasteful number, since it uses less digits than its factorization.

228291991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154808.

The product of its digits is 46656, while the sum is 43.

The square root of 228291991 is about 15109.3345650958. The cubic root of 228291991 is about 611.1721536073.

The spelling of 228291991 in words is "two hundred twenty-eight million, two hundred ninety-one thousand, nine hundred ninety-one".