20406638 has 12 divisors (see below), whose sum is σ = 35607672. Its totient is φ = 8745660.

The previous prime is 20406611. The next prime is 20406641. The reversal of 20406638 is 83660402.

It is a self number, because there is not a number n which added to its sum of digits gives 20406638.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 104018 + ... + 104213.

It is an arithmetic number, because the mean of its divisors is an integer number (2967306).

Almost surely, 2^20406638 is an apocalyptic number.

20406638 is a deficient number, since it is larger than the sum of its proper divisors (15201034).

20406638 is a wasteful number, since it uses less digits than its factorization.

20406638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208247 (or 208240 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 20406638 is about 4517.3706954378. The cubic root of 20406638 is about 273.2690750526.

The spelling of 20406638 in words is "twenty million, four hundred six thousand, six hundred thirty-eight".