28449781 has 16 divisors (see below), whose sum is σ = 30883968. Its totient is φ = 26136000.

The previous prime is 28449769. The next prime is 28449787. The reversal of 28449781 is 18794482.

It is a cyclic number.

It is not a de Polignac number, because 28449781 - 2⁵ = 28449749 is a prime.

It is a super-2 number, since 2×28449781² = 1618780077895922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28449787) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85786 + ... + 86116.

It is an arithmetic number, because the mean of its divisors is an integer number (1930248).

Almost surely, 2^28449781 is an apocalyptic number.

It is an amenable number.

28449781 is a deficient number, since it is larger than the sum of its proper divisors (2434187).

28449781 is a wasteful number, since it uses less digits than its factorization.

28449781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492.

The product of its digits is 129024, while the sum is 43.

The square root of 28449781 is about 5333.8336119530. The cubic root of 28449781 is about 305.2762202512.

The spelling of 28449781 in words is "twenty-eight million, four hundred forty-nine thousand, seven hundred eighty-one".