20987255 has 8 divisors (see below), whose sum is σ = 25229232. Its totient is φ = 16760128.

The previous prime is 20987249. The next prime is 20987257. The reversal of 20987255 is 55278902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20987255 - 2¹² = 20983159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20987257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 317 + ... + 6486.

It is an arithmetic number, because the mean of its divisors is an integer number (3153654).

Almost surely, 2^20987255 is an apocalyptic number.

20987255 is a deficient number, since it is larger than the sum of its proper divisors (4241977).

20987255 is an equidigital number, since it uses as much as digits as its factorization.

20987255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7425.

The product of its (nonzero) digits is 50400, while the sum is 38.

The square root of 20987255 is about 4581.1848903968. The cubic root of 20987255 is about 275.8365928691.

The spelling of 20987255 in words is "twenty million, nine hundred eighty-seven thousand, two hundred fifty-five".