20015491 has 4 divisors (see below), whose sum is σ = 20661184. Its totient is φ = 19369800.

The previous prime is 20015461. The next prime is 20015507. The reversal of 20015491 is 19451002.

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 20015491 - 2⁷ = 20015363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20015431) 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, 322800 + ... + 322861.

It is an arithmetic number, because the mean of its divisors is an integer number (5165296).

Almost surely, 2^20015491 is an apocalyptic number.

20015491 is a deficient number, since it is larger than the sum of its proper divisors (645693).

20015491 is an equidigital number, since it uses as much as digits as its factorization.

20015491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645692.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 20015491 is about 4473.8675662116. The cubic root of 20015491 is about 271.5118253122.

Adding to 20015491 its reverse (19451002), we get a palindrome (39466493).

The spelling of 20015491 in words is "twenty million, fifteen thousand, four hundred ninety-one".