20640445 has 16 divisors (see below), whose sum is σ = 28435968. Its totient is φ = 14088960.

The previous prime is 20640443. The next prime is 20640449. The reversal of 20640445 is 54404602.

It is not a de Polignac number, because 20640445 - 2¹ = 20640443 is a prime.

It is a super-3 number, since 3×20640445³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7212 + ... + 9658.

It is an arithmetic number, because the mean of its divisors is an integer number (1777248).

Almost surely, 2^20640445 is an apocalyptic number.

It is an amenable number.

20640445 is a deficient number, since it is larger than the sum of its proper divisors (7795523).

20640445 is a wasteful number, since it uses less digits than its factorization.

20640445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2700.

The product of its (nonzero) digits is 3840, while the sum is 25.

The square root of 20640445 is about 4543.1756514579. The cubic root of 20640445 is about 274.3087653592.

The spelling of 20640445 in words is "twenty million, six hundred forty thousand, four hundred forty-five".