20666655 has 24 divisors (see below), whose sum is σ = 35981712. Its totient is φ = 10973184.

The previous prime is 20666651. The next prime is 20666669. The reversal of 20666655 is 55666602.

It is not a de Polignac number, because 20666655 - 2² = 20666651 is a prime.

It is a super-2 number, since 2×20666655² = 854221257778050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20666651) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10672 + ... + 12458.

It is an arithmetic number, because the mean of its divisors is an integer number (1499238).

Almost surely, 2^20666655 is an apocalyptic number.

20666655 is a deficient number, since it is larger than the sum of its proper divisors (15315057).

20666655 is a wasteful number, since it uses less digits than its factorization.

20666655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2055 (or 2052 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The square root of 20666655 is about 4546.0592824995. The cubic root of 20666655 is about 274.4248253839.

It can be divided in two parts, 20666 and 655, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 20666655 in words is "twenty million, six hundred sixty-six thousand, six hundred fifty-five".