20115491 has 4 divisors (see below), whose sum is σ = 21944184. Its totient is φ = 18286800.

The previous prime is 20115481. The next prime is 20115493. The reversal of 20115491 is 19451102.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20115491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20115493) 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, 914330 + ... + 914351.

It is an arithmetic number, because the mean of its divisors is an integer number (5486046).

Almost surely, 2^20115491 is an apocalyptic number.

20115491 is a deficient number, since it is larger than the sum of its proper divisors (1828693).

20115491 is a wasteful number, since it uses less digits than its factorization.

20115491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1828692.

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

The square root of 20115491 is about 4485.0296543055. The cubic root of 20115491 is about 271.9632438438.

Adding to 20115491 its reverse (19451102), we get a palindrome (39566593).

It can be divided in two parts, 20 and 115491, that added together give a palindrome (115511).

The spelling of 20115491 in words is "twenty million, one hundred fifteen thousand, four hundred ninety-one".