28308381 has 8 divisors (see below), whose sum is σ = 38118624. Its totient is φ = 18685200.

The previous prime is 28308359. The next prime is 28308403. The reversal of 28308381 is 18380382.

It is an interprime number because it is at equal distance from previous prime (28308359) and next prime (28308403).

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

It is not a de Polignac number, because 28308381 - 2⁷ = 28308253 is a prime.

It is a super-2 number, since 2×28308381² = 1602728869682322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28308311) 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, 46411 + ... + 47016.

It is an arithmetic number, because the mean of its divisors is an integer number (4764828).

Almost surely, 2^28308381 is an apocalyptic number.

It is an amenable number.

28308381 is a deficient number, since it is larger than the sum of its proper divisors (9810243).

28308381 is a wasteful number, since it uses less digits than its factorization.

28308381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93531.

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 28308381 is about 5320.5620943656. The cubic root of 28308381 is about 304.7696226813.

It can be divided in two parts, 2830 and 8381, that added together give a palindrome (11211).

The spelling of 28308381 in words is "twenty-eight million, three hundred eight thousand, three hundred eighty-one".