20530391 has 4 divisors (see below), whose sum is σ = 23463312. Its totient is φ = 17597472.

The previous prime is 20530351. The next prime is 20530397. The reversal of 20530391 is 19303502.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20530391 - 2⁶ = 20530327 is a prime.

It is a super-2 number, since 2×20530391² = 842993909225762, 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 (20530397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1466450 + ... + 1466463.

It is an arithmetic number, because the mean of its divisors is an integer number (5865828).

Almost surely, 2^20530391 is an apocalyptic number.

20530391 is a deficient number, since it is larger than the sum of its proper divisors (2932921).

20530391 is an equidigital number, since it uses as much as digits as its factorization.

20530391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2932920.

The product of its (nonzero) digits is 810, while the sum is 23.

The square root of 20530391 is about 4531.0474506454. The cubic root of 20530391 is about 273.8203619443.

Adding to 20530391 its reverse (19303502), we get a palindrome (39833893).

The spelling of 20530391 in words is "twenty million, five hundred thirty thousand, three hundred ninety-one".