20661255 has 24 divisors (see below), whose sum is σ = 36492768. Its totient is φ = 10810176.

The previous prime is 20661241. The next prime is 20661257. The reversal of 20661255 is 55216602.

It is not a de Polignac number, because 20661255 - 2⁶ = 20661191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1947 + ... + 6716.

It is an arithmetic number, because the mean of its divisors is an integer number (1520532).

Almost surely, 2^20661255 is an apocalyptic number.

20661255 is a deficient number, since it is larger than the sum of its proper divisors (15831513).

20661255 is a wasteful number, since it uses less digits than its factorization.

20661255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8727 (or 8724 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 20661255 is about 4545.4653227145. The cubic root of 20661255 is about 274.4009217713.

Adding to 20661255 its reverse (55216602), we get a palindrome (75877857).

It can be divided in two parts, 2066 and 1255, that added together give a triangular number (3321 = T₈₁).

The spelling of 20661255 in words is "twenty million, six hundred sixty-one thousand, two hundred fifty-five".