28671581 has 4 divisors (see below), whose sum is σ = 29157600. Its totient is φ = 28185564.

The previous prime is 28671557. The next prime is 28671611. The reversal of 28671581 is 18517682.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18517682 = 2 ⋅9258841.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28671581 is a prime.

It is a super-2 number, since 2×28671581² = 1644119114079122, 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 (28671521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 242921 + ... + 243038.

It is an arithmetic number, because the mean of its divisors is an integer number (7289400).

Almost surely, 2^28671581 is an apocalyptic number.

It is an amenable number.

28671581 is a deficient number, since it is larger than the sum of its proper divisors (486019).

28671581 is an equidigital number, since it uses as much as digits as its factorization.

28671581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486018.

The product of its digits is 26880, while the sum is 38.

The square root of 28671581 is about 5354.5850446136. The cubic root of 28671581 is about 306.0674983171.

The spelling of 28671581 in words is "twenty-eight million, six hundred seventy-one thousand, five hundred eighty-one".