28699221 has 8 divisors (see below), whose sum is σ = 39199104. Its totient is φ = 18666080.

The previous prime is 28699217. The next prime is 28699243. The reversal of 28699221 is 12299682.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28699221 - 2² = 28699217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28699221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28699201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 116541 + ... + 116786.

It is an arithmetic number, because the mean of its divisors is an integer number (4899888).

Almost surely, 2^28699221 is an apocalyptic number.

It is an amenable number.

28699221 is a deficient number, since it is larger than the sum of its proper divisors (10499883).

28699221 is a wasteful number, since it uses less digits than its factorization.

28699221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233371.

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

The square root of 28699221 is about 5357.1653885240. The cubic root of 28699221 is about 306.1658185395.

It can be divided in two parts, 28699 and 221, that added together give a triangular number (28920 = T₂₄₀).

The spelling of 28699221 in words is "twenty-eight million, six hundred ninety-nine thousand, two hundred twenty-one".