28757081 has 4 divisors (see below), whose sum is σ = 30448692. Its totient is φ = 27065472.

The previous prime is 28757077. The next prime is 28757083. The reversal of 28757081 is 18075782.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18075782 = 2 ⋅9037891.

It can be written as a sum of positive squares in 2 ways, for example, as 10137856 + 18619225 = 3184^2 + 4315^2 .

It is a cyclic number.

It is not a de Polignac number, because 28757081 - 2² = 28757077 is a prime.

It is a super-2 number, since 2×28757081² = 1653939415281122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28757083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 845780 + ... + 845813.

It is an arithmetic number, because the mean of its divisors is an integer number (7612173).

Almost surely, 2^28757081 is an apocalyptic number.

It is an amenable number.

28757081 is a deficient number, since it is larger than the sum of its proper divisors (1691611).

28757081 is a wasteful number, since it uses less digits than its factorization.

28757081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1691610.

The product of its (nonzero) digits is 31360, while the sum is 38.

The square root of 28757081 is about 5362.5629133839. The cubic root of 28757081 is about 306.3714322828.

The spelling of 28757081 in words is "twenty-eight million, seven hundred fifty-seven thousand, eighty-one".