20871155 has 16 divisors (see below), whose sum is σ = 27436320. Its totient is φ = 15171072.

The previous prime is 20871133. The next prime is 20871157. The reversal of 20871155 is 55117802.

It is not a de Polignac number, because 20871155 - 2¹⁸ = 20609011 is a prime.

It is a super-2 number, since 2×20871155² = 871210222068050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is not an unprimeable number, because it can be changed into a prime (20871157) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1769 + ... + 6698.

It is an arithmetic number, because the mean of its divisors is an integer number (1714770).

Almost surely, 2^20871155 is an apocalyptic number.

20871155 is a deficient number, since it is larger than the sum of its proper divisors (6565165).

20871155 is a wasteful number, since it uses less digits than its factorization.

20871155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8518.

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 20871155 is about 4568.4959231677. The cubic root of 20871155 is about 275.3270159339.

Adding to 20871155 its reverse (55117802), we get a palindrome (75988957).

The spelling of 20871155 in words is "twenty million, eight hundred seventy-one thousand, one hundred fifty-five".