221228929 has 4 divisors (see below), whose sum is σ = 221531476. Its totient is φ = 220926384.

The previous prime is 221228923. The next prime is 221228963. The reversal of 221228929 is 929822122.

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 185504400 + 35724529 = 13620^2 + 5977^2 .

It is a cyclic number.

It is not a de Polignac number, because 221228929 - 2⁹ = 221228417 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (221228923) 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, 150174 + ... + 151639.

It is an arithmetic number, because the mean of its divisors is an integer number (55382869).

Almost surely, 2^221228929 is an apocalyptic number.

It is an amenable number.

221228929 is a deficient number, since it is larger than the sum of its proper divisors (302547).

221228929 is an equidigital number, since it uses as much as digits as its factorization.

221228929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302546.

The product of its digits is 20736, while the sum is 37.

The square root of 221228929 is about 14873.7664698623. The cubic root of 221228929 is about 604.8030495228.

The spelling of 221228929 in words is "two hundred twenty-one million, two hundred twenty-eight thousand, nine hundred twenty-nine".