28781081 has 12 divisors (see below), whose sum is σ = 34032420. Its totient is φ = 24262560.

The previous prime is 28781063. The next prime is 28781099. The reversal of 28781081 is 18018782.

It is an interprime number because it is at equal distance from previous prime (28781063) and next prime (28781099).

It can be written as a sum of positive squares in 2 ways, for example, as 15531481 + 13249600 = 3941^2 + 3640^2 .

It is not a de Polignac number, because 28781081 - 2¹⁰ = 28780057 is a prime.

It is a super-2 number, since 2×28781081² = 1656701247057122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28781041) 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 11 ways as a sum of consecutive naturals, for example, 1826 + ... + 7803.

It is an arithmetic number, because the mean of its divisors is an integer number (2836035).

Almost surely, 2^28781081 is an apocalyptic number.

It is an amenable number.

28781081 is a deficient number, since it is larger than the sum of its proper divisors (5251339).

28781081 is an equidigital number, since it uses as much as digits as its factorization.

28781081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9704 (or 9697 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 28781081 is about 5364.8001826722. The cubic root of 28781081 is about 306.4566387727.

The spelling of 28781081 in words is "twenty-eight million, seven hundred eighty-one thousand, eighty-one".