20391145 has 8 divisors (see below), whose sum is σ = 25066440. Its totient is φ = 15914880.

The previous prime is 20391139. The next prime is 20391157. The reversal of 20391145 is 54119302.

It can be written as a sum of positive squares in 4 ways, for example, as 249001 + 20142144 = 499^2 + 4488^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20391145 - 2¹¹ = 20389097 is a prime.

It is a super-2 number, since 2×20391145² = 831597588822050, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49530 + ... + 49939.

It is an arithmetic number, because the mean of its divisors is an integer number (3133305).

Almost surely, 2^20391145 is an apocalyptic number.

It is an amenable number.

20391145 is a deficient number, since it is larger than the sum of its proper divisors (4675295).

20391145 is an equidigital number, since it uses as much as digits as its factorization.

20391145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99515.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 20391145 is about 4515.6555448794. The cubic root of 20391145 is about 273.1999009980.

The spelling of 20391145 in words is "twenty million, three hundred ninety-one thousand, one hundred forty-five".