20408247 has 8 divisors (see below), whose sum is σ = 30234480. Its totient is φ = 13605480.

The previous prime is 20408243. The next prime is 20408263. The reversal of 20408247 is 74280402.

It is not a de Polignac number, because 20408247 - 2² = 20408243 is a prime.

It is a super-2 number, since 2×20408247² = 832993091226018, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 755861 = 20408247 / (2 + 0 + 4 + 0 + 8 + 2 + 4 + 7).

It is a self number, because there is not a number n which added to its sum of digits gives 20408247.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20408243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 377904 + ... + 377957.

It is an arithmetic number, because the mean of its divisors is an integer number (3779310).

Almost surely, 2^20408247 is an apocalyptic number.

20408247 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

20408247 is a deficient number, since it is larger than the sum of its proper divisors (9826233).

20408247 is an equidigital number, since it uses as much as digits as its factorization.

20408247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755870 (or 755864 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 27.

The square root of 20408247 is about 4517.5487822491. The cubic root of 20408247 is about 273.2762570030.

Adding to 20408247 its reverse (74280402), we get a palindrome (94688649).

The spelling of 20408247 in words is "twenty million, four hundred eight thousand, two hundred forty-seven".