20236391 has 4 divisors (see below), whose sum is σ = 23127312. Its totient is φ = 17345472.

The previous prime is 20236361. The next prime is 20236423. The reversal of 20236391 is 19363202.

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 20236391 - 2⁶ = 20236327 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20236391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20236361) 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, 1445450 + ... + 1445463.

It is an arithmetic number, because the mean of its divisors is an integer number (5781828).

Almost surely, 2^20236391 is an apocalyptic number.

20236391 is a deficient number, since it is larger than the sum of its proper divisors (2890921).

20236391 is an equidigital number, since it uses as much as digits as its factorization.

20236391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2890920.

The product of its (nonzero) digits is 1944, while the sum is 26.

The square root of 20236391 is about 4498.4876347502. The cubic root of 20236391 is about 272.5070155027.

Adding to 20236391 its reverse (19363202), we get a palindrome (39599593).

The spelling of 20236391 in words is "twenty million, two hundred thirty-six thousand, three hundred ninety-one".