20406247 has 6 divisors (see below), whose sum is σ = 21537168. Its totient is φ = 19331892.

The previous prime is 20406229. The next prime is 20406259. The reversal of 20406247 is 74260402.

It is not a de Polignac number, because 20406247 - 2⁷ = 20406119 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 (20409247) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 27903 + ... + 28624.

It is an arithmetic number, because the mean of its divisors is an integer number (3589528).

Almost surely, 2^20406247 is an apocalyptic number.

20406247 is a deficient number, since it is larger than the sum of its proper divisors (1130921).

20406247 is an equidigital number, since it uses as much as digits as its factorization.

20406247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56565 (or 56546 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 25.

The square root of 20406247 is about 4517.3274178434. The cubic root of 20406247 is about 273.2673297236.

Adding to 20406247 its reverse (74260402), we get a palindrome (94666649).

The spelling of 20406247 in words is "twenty million, four hundred six thousand, two hundred forty-seven".