28915861 has 8 divisors (see below), whose sum is σ = 32972184. Its totient is φ = 25121280.

The previous prime is 28915849. The next prime is 28915867. The reversal of 28915861 is 16851982.

It can be written as a sum of positive squares in 4 ways, for example, as 78961 + 28836900 = 281^2 + 5370^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28915861 - 2¹⁵ = 28883093 is a prime.

It is a super-2 number, since 2×28915861² = 1672254034742642, 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 (28915867) 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 7 ways as a sum of consecutive naturals, for example, 65200 + ... + 65641.

It is an arithmetic number, because the mean of its divisors is an integer number (4121523).

Almost surely, 2^28915861 is an apocalyptic number.

It is an amenable number.

28915861 is a deficient number, since it is larger than the sum of its proper divisors (4056323).

28915861 is a wasteful number, since it uses less digits than its factorization.

28915861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130871.

The product of its digits is 34560, while the sum is 40.

The square root of 28915861 is about 5377.3470224638. The cubic root of 28915861 is about 306.9342663962.

The spelling of 28915861 in words is "twenty-eight million, nine hundred fifteen thousand, eight hundred sixty-one".