28821691 has 8 divisors (see below), whose sum is σ = 30232224. Its totient is φ = 27424320.

The previous prime is 28821673. The next prime is 28821701. The reversal of 28821691 is 19612882.

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 28821691 - 2¹⁷ = 28690619 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 28821691.

It is not an unprimeable number, because it can be changed into a prime (28821601) 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, 1351 + ... + 7711.

It is an arithmetic number, because the mean of its divisors is an integer number (3779028).

Almost surely, 2^28821691 is an apocalyptic number.

28821691 is a deficient number, since it is larger than the sum of its proper divisors (1410533).

28821691 is a wasteful number, since it uses less digits than its factorization.

28821691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6581.

The product of its digits is 13824, while the sum is 37.

The square root of 28821691 is about 5368.5837052243. The cubic root of 28821691 is about 306.6007074326.

The spelling of 28821691 in words is "twenty-eight million, eight hundred twenty-one thousand, six hundred ninety-one".