28020381 has 4 divisors (see below), whose sum is σ = 37360512. Its totient is φ = 18680252.

The previous prime is 28020379. The next prime is 28020397. The reversal of 28020381 is 18302082.

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.

It is a cyclic number.

It is not a de Polignac number, because 28020381 - 2¹ = 28020379 is a prime.

It is a super-2 number, since 2×28020381² = 1570283502770322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28020331) 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, 4670061 + ... + 4670066.

It is an arithmetic number, because the mean of its divisors is an integer number (9340128).

Almost surely, 2^28020381 is an apocalyptic number.

It is an amenable number.

28020381 is a deficient number, since it is larger than the sum of its proper divisors (9340131).

28020381 is an equidigital number, since it uses as much as digits as its factorization.

28020381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9340130.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 28020381 is about 5293.4280952895. The cubic root of 28020381 is about 303.7325563659.

The spelling of 28020381 in words is "twenty-eight million, twenty thousand, three hundred eighty-one".