20561830 has 16 divisors (see below), whose sum is σ = 37099584. Its totient is φ = 8205120.

The previous prime is 20561809. The next prime is 20561833. The reversal of 20561830 is 3816502.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 20561795 and 20561804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561833) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2410 + ... + 6850.

It is an arithmetic number, because the mean of its divisors is an integer number (2318724).

Almost surely, 2^20561830 is an apocalyptic number.

20561830 is a deficient number, since it is larger than the sum of its proper divisors (16537754).

20561830 is a wasteful number, since it uses less digits than its factorization.

20561830 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4911.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 20561830 is about 4534.5154096110. The cubic root of 20561830 is about 273.9600613107.

The spelling of 20561830 in words is "twenty million, five hundred sixty-one thousand, eight hundred thirty".