28996221 has 4 divisors (see below), whose sum is σ = 38661632. Its totient is φ = 19330812.

The previous prime is 28996217. The next prime is 28996229. The reversal of 28996221 is 12269982.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 28996221 - 2² = 28996217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28996221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28996229) 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, 4832701 + ... + 4832706.

It is an arithmetic number, because the mean of its divisors is an integer number (9665408).

Almost surely, 2^28996221 is an apocalyptic number.

It is an amenable number.

28996221 is a deficient number, since it is larger than the sum of its proper divisors (9665411).

28996221 is an equidigital number, since it uses as much as digits as its factorization.

28996221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9665410.

The product of its digits is 31104, while the sum is 39.

The square root of 28996221 is about 5384.8139243617. The cubic root of 28996221 is about 307.2183368334.

The spelling of 28996221 in words is "twenty-eight million, nine hundred ninety-six thousand, two hundred twenty-one".