20028391 has 2 divisors, whose sum is σ = 20028392. Its totient is φ = 20028390.

The previous prime is 20028389. The next prime is 20028409. The reversal of 20028391 is 19382002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20028391 - 2¹ = 20028389 is a prime.

It is a super-2 number, since 2×20028391² = 802272892097762, which contains 22 as substring.

Together with 20028389, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20028301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10014195 + 10014196.

It is an arithmetic number, because the mean of its divisors is an integer number (10014196).

Almost surely, 2^20028391 is an apocalyptic number.

20028391 is a deficient number, since it is larger than the sum of its proper divisors (1).

20028391 is an equidigital number, since it uses as much as digits as its factorization.

20028391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 20028391 is about 4475.3090396083. The cubic root of 20028391 is about 271.5701426485.

The spelling of 20028391 in words is "twenty million, twenty-eight thousand, three hundred ninety-one".