20451191 has 4 divisors (see below), whose sum is σ = 20612352. Its totient is φ = 20290032.

The previous prime is 20451181. The next prime is 20451199. The reversal of 20451191 is 19115402.

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 20451191 - 2⁶ = 20451127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20451199) 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, 80390 + ... + 80643.

It is an arithmetic number, because the mean of its divisors is an integer number (5153088).

Almost surely, 2^20451191 is an apocalyptic number.

20451191 is a deficient number, since it is larger than the sum of its proper divisors (161161).

20451191 is a wasteful number, since it uses less digits than its factorization.

20451191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161160.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 20451191 is about 4522.2993045574. The cubic root of 20451191 is about 273.4678029937.

Adding to 20451191 its reverse (19115402), we get a palindrome (39566593).

The spelling of 20451191 in words is "twenty million, four hundred fifty-one thousand, one hundred ninety-one".