28629221 has 4 divisors (see below), whose sum is σ = 28719852. Its totient is φ = 28538592.

The previous prime is 28629217. The next prime is 28629277. The reversal of 28629221 is 12292682.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12292682 = 2 ⋅6146341.

It can be written as a sum of positive squares in 2 ways, for example, as 422500 + 28206721 = 650^2 + 5311^2 .

It is a cyclic number.

It is not a de Polignac number, because 28629221 - 2² = 28629217 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 (28629121) 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, 44840 + ... + 45473.

It is an arithmetic number, because the mean of its divisors is an integer number (7179963).

Almost surely, 2^28629221 is an apocalyptic number.

It is an amenable number.

28629221 is a deficient number, since it is larger than the sum of its proper divisors (90631).

28629221 is an equidigital number, since it uses as much as digits as its factorization.

28629221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90630.

The product of its digits is 6912, while the sum is 32.

The square root of 28629221 is about 5350.6280939718. The cubic root of 28629221 is about 305.9166938276.

The spelling of 28629221 in words is "twenty-eight million, six hundred twenty-nine thousand, two hundred twenty-one".