20203691 has 4 divisors (see below), whose sum is σ = 20900400. Its totient is φ = 19506984.

The previous prime is 20203657. The next prime is 20203709. The reversal of 20203691 is 19630202.

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 20203691 - 2¹⁰ = 20202667 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (20203621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 348311 + ... + 348368.

It is an arithmetic number, because the mean of its divisors is an integer number (5225100).

Almost surely, 2^20203691 is an apocalyptic number.

20203691 is a deficient number, since it is larger than the sum of its proper divisors (696709).

20203691 is an equidigital number, since it uses as much as digits as its factorization.

20203691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 696708.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 20203691 is about 4494.8516104539. The cubic root of 20203691 is about 272.3601549373.

Adding to 20203691 its reverse (19630202), we get a palindrome (39833893).

The spelling of 20203691 in words is "twenty million, two hundred three thousand, six hundred ninety-one".