20861655 has 32 divisors (see below), whose sum is σ = 34504704. Its totient is φ = 10757376.

The previous prime is 20861653. The next prime is 20861663. The reversal of 20861655 is 55616802.

It is not a de Polignac number, because 20861655 - 2¹ = 20861653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20861653) 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, 89419 + ... + 89651.

It is an arithmetic number, because the mean of its divisors is an integer number (1078272).

Almost surely, 2^20861655 is an apocalyptic number.

20861655 is a deficient number, since it is larger than the sum of its proper divisors (13643049).

20861655 is a wasteful number, since it uses less digits than its factorization.

20861655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415.

The product of its (nonzero) digits is 14400, while the sum is 33.

The square root of 20861655 is about 4567.4560753225. The cubic root of 20861655 is about 275.2852357257.

It can be divided in two parts, 2086 and 1655, that added together give a triangular number (3741 = T₈₆).

The spelling of 20861655 in words is "twenty million, eight hundred sixty-one thousand, six hundred fifty-five".