20406639 has 32 divisors (see below), whose sum is σ = 30945024. Its totient is φ = 11854080.

The previous prime is 20406611. The next prime is 20406641. The reversal of 20406639 is 93660402.

It is not a de Polignac number, because 20406639 - 2⁸ = 20406383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20406679) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 103489 + ... + 103685.

It is an arithmetic number, because the mean of its divisors is an integer number (967032).

Almost surely, 2^20406639 is an apocalyptic number.

20406639 is a deficient number, since it is larger than the sum of its proper divisors (10538385).

20406639 is a wasteful number, since it uses less digits than its factorization.

20406639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 327.

The product of its (nonzero) digits is 7776, while the sum is 30.

The square root of 20406639 is about 4517.3708061216. The cubic root of 20406639 is about 273.2690795163.

The spelling of 20406639 in words is "twenty million, four hundred six thousand, six hundred thirty-nine".