20891255 has 24 divisors (see below), whose sum is σ = 31498656. Its totient is φ = 13020480.

The previous prime is 20891239. The next prime is 20891257. The reversal of 20891255 is 55219802.

It is not a de Polignac number, because 20891255 - 2⁴ = 20891239 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20891257) 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, 1769 + ... + 6701.

It is an arithmetic number, because the mean of its divisors is an integer number (1312444).

Almost surely, 2^20891255 is an apocalyptic number.

20891255 is a deficient number, since it is larger than the sum of its proper divisors (10607401).

20891255 is a wasteful number, since it uses less digits than its factorization.

20891255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4967 (or 4956 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 20891255 is about 4570.6952425206. The cubic root of 20891255 is about 275.4153722873.

The spelling of 20891255 in words is "twenty million, eight hundred ninety-one thousand, two hundred fifty-five".