20640606 has 64 divisors (see below), whose sum is σ = 49545216. Its totient is φ = 5608800.

The previous prime is 20640583. The next prime is 20640617. The reversal of 20640606 is 60604602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 107971 + ... + 108161.

It is an arithmetic number, because the mean of its divisors is an integer number (774144).

Almost surely, 2^20640606 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20640606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24772608).

20640606 is an abundant number, since it is smaller than the sum of its proper divisors (28904610).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20640606 is a wasteful number, since it uses less digits than its factorization.

20640606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 317.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 20640606 is about 4543.1933703068. The cubic root of 20640606 is about 274.3094785802.

The spelling of 20640606 in words is "twenty million, six hundred forty thousand, six hundred six".