20406213 has 12 divisors (see below), whose sum is σ = 29517228. Its totient is φ = 13584960.

The previous prime is 20406167. The next prime is 20406223. The reversal of 20406213 is 31260402.

It is a happy number.

20406213 is a `hidden beast` number, since 2 + 0 + 40 + 621 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6140484 + 14265729 = 2478^2 + 3777^2 .

It is not a de Polignac number, because 20406213 - 2⁶ = 20406149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20406223) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8481 + ... + 10617.

It is an arithmetic number, because the mean of its divisors is an integer number (2459769).

Almost surely, 2^20406213 is an apocalyptic number.

It is an amenable number.

20406213 is a deficient number, since it is larger than the sum of its proper divisors (9111015).

20406213 is a wasteful number, since it uses less digits than its factorization.

20406213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3204 (or 3201 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 20406213 is about 4517.3236545548. The cubic root of 20406213 is about 273.2671779548.

Adding to 20406213 its reverse (31260402), we get a palindrome (51666615).

The spelling of 20406213 in words is "twenty million, four hundred six thousand, two hundred thirteen".