28204381 has 4 divisors (see below), whose sum is σ = 28309500. Its totient is φ = 28099264.

The previous prime is 28204369. The next prime is 28204391. The reversal of 28204381 is 18340282.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2102500 + 26101881 = 1450^2 + 5109^2 .

It is a cyclic number.

It is not a de Polignac number, because 28204381 - 2⁵ = 28204349 is a prime.

It is a super-2 number, since 2×28204381² = 1590974215186322, 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 (28204331) 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, 52156 + ... + 52693.

It is an arithmetic number, because the mean of its divisors is an integer number (7077375).

Almost surely, 2^28204381 is an apocalyptic number.

It is an amenable number.

28204381 is a deficient number, since it is larger than the sum of its proper divisors (105119).

28204381 is a wasteful number, since it uses less digits than its factorization.

28204381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105118.

The product of its (nonzero) digits is 3072, while the sum is 28.

The square root of 28204381 is about 5310.7796979351. The cubic root of 28204381 is about 304.3959414100.

The spelling of 28204381 in words is "twenty-eight million, two hundred four thousand, three hundred eighty-one".