20188491 has 4 divisors (see below), whose sum is σ = 26917992. Its totient is φ = 13458992.

The previous prime is 20188489. The next prime is 20188501. The reversal of 20188491 is 19488102.

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 20188491 - 2¹ = 20188489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20188451) 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, 3364746 + ... + 3364751.

It is an arithmetic number, because the mean of its divisors is an integer number (6729498).

Almost surely, 2^20188491 is an apocalyptic number.

20188491 is a deficient number, since it is larger than the sum of its proper divisors (6729501).

20188491 is an equidigital number, since it uses as much as digits as its factorization.

20188491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6729500.

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 20188491 is about 4493.1604689795. The cubic root of 20188491 is about 272.2918355234.

The spelling of 20188491 in words is "twenty million, one hundred eighty-eight thousand, four hundred ninety-one".