20561255 has 32 divisors (see below), whose sum is σ = 29332800. Its totient is φ = 13639680.

The previous prime is 20561239. The next prime is 20561257. The reversal of 20561255 is 55216502.

It is not a de Polignac number, because 20561255 - 2⁴ = 20561239 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561257) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 106439 + ... + 106631.

It is an arithmetic number, because the mean of its divisors is an integer number (916650).

Almost surely, 2^20561255 is an apocalyptic number.

20561255 is a deficient number, since it is larger than the sum of its proper divisors (8771545).

20561255 is a wasteful number, since it uses less digits than its factorization.

20561255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371.

The product of its (nonzero) digits is 3000, while the sum is 26.

The square root of 20561255 is about 4534.4520065825. The cubic root of 20561255 is about 273.9575075740.

Adding to 20561255 its reverse (55216502), we get a palindrome (75777757).

The spelling of 20561255 in words is "twenty million, five hundred sixty-one thousand, two hundred fifty-five".