28721619 has 24 divisors (see below), whose sum is σ = 44293392. Its totient is φ = 17871360.

The previous prime is 28721617. The next prime is 28721647. The reversal of 28721619 is 91612782.

It is not a de Polignac number, because 28721619 - 2¹ = 28721617 is a prime.

It is a super-2 number, since 2×28721619² = 1649862795962322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28721611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19327 + ... + 20759.

It is an arithmetic number, because the mean of its divisors is an integer number (1845558).

Almost surely, 2^28721619 is an apocalyptic number.

28721619 is a deficient number, since it is larger than the sum of its proper divisors (15571773).

28721619 is a wasteful number, since it uses less digits than its factorization.

28721619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1587 (or 1584 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 28721619 is about 5359.2554520194. The cubic root of 28721619 is about 306.2454457743.

The spelling of 28721619 in words is "twenty-eight million, seven hundred twenty-one thousand, six hundred nineteen".