20641209 has 16 divisors (see below), whose sum is σ = 28155840. Its totient is φ = 13446720.

The previous prime is 20641207. The next prime is 20641211. The reversal of 20641209 is 90214602.

It is an interprime number because it is at equal distance from previous prime (20641207) and next prime (20641211).

It is not a de Polignac number, because 20641209 - 2¹ = 20641207 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20641207) 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, 48819 + ... + 49239.

It is an arithmetic number, because the mean of its divisors is an integer number (1759740).

Almost surely, 2^20641209 is an apocalyptic number.

It is an amenable number.

20641209 is a deficient number, since it is larger than the sum of its proper divisors (7514631).

20641209 is a wasteful number, since it uses less digits than its factorization.

20641209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 760.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 20641209 is about 4543.2597328350. The cubic root of 20641209 is about 274.3121498036.

The spelling of 20641209 in words is "twenty million, six hundred forty-one thousand, two hundred nine".