28138481 has 8 divisors (see below), whose sum is σ = 32200320. Its totient is φ = 24087168.

The previous prime is 28138471. The next prime is 28138493. The reversal of 28138481 is 18483182.

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

It is a de Polignac number, because none of the positive numbers 2^k-28138481 is a prime.

It is a super-2 number, since 2×28138481² = 1583548225974722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28138471) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4340 + ... + 8666.

It is an arithmetic number, because the mean of its divisors is an integer number (4025040).

Almost surely, 2^28138481 is an apocalyptic number.

It is an amenable number.

28138481 is a deficient number, since it is larger than the sum of its proper divisors (4061839).

28138481 is an equidigital number, since it uses as much as digits as its factorization.

28138481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5263.

The product of its digits is 12288, while the sum is 35.

The square root of 28138481 is about 5304.5717074991. The cubic root of 28138481 is about 304.1586811523.

The spelling of 28138481 in words is "twenty-eight million, one hundred thirty-eight thousand, four hundred eighty-one".