20561236 has 12 divisors (see below), whose sum is σ = 36257760. Its totient is φ = 10201880.

The previous prime is 20561221. The next prime is 20561237. The reversal of 20561236 is 63216502.

It is a self number, because there is not a number n which added to its sum of digits gives 20561236.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19096 + ... + 20143.

It is an arithmetic number, because the mean of its divisors is an integer number (3021480).

Almost surely, 2^20561236 is an apocalyptic number.

It is an amenable number.

20561236 is a deficient number, since it is larger than the sum of its proper divisors (15696524).

20561236 is a wasteful number, since it uses less digits than its factorization.

20561236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39374 (or 39372 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 20561236 is about 4534.4499115108. The cubic root of 20561236 is about 273.9574231888.

Adding to 20561236 its reverse (63216502), we get a palindrome (83777738).

The spelling of 20561236 in words is "twenty million, five hundred sixty-one thousand, two hundred thirty-six".