21113155 has 16 divisors (see below), whose sum is σ = 29663424. Its totient is φ = 14123520.

The previous prime is 21113153. The next prime is 21113159. The reversal of 21113155 is 55131112.

It is not a de Polignac number, because 21113155 - 2¹ = 21113153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21113153) 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, 5922 + ... + 8791.

It is an arithmetic number, because the mean of its divisors is an integer number (1853964).

Almost surely, 2^21113155 is an apocalyptic number.

21113155 is a deficient number, since it is larger than the sum of its proper divisors (8550269).

21113155 is a wasteful number, since it uses less digits than its factorization.

21113155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14766.

The product of its digits is 150, while the sum is 19.

The square root of 21113155 is about 4594.9053309073. The cubic root of 21113155 is about 276.3870636966.

Adding to 21113155 its reverse (55131112), we get a palindrome (76244267).

It can be divided in two parts, 211 and 13155, that added together give a triangular number (13366 = T₁₆₃).

The spelling of 21113155 in words is "twenty-one million, one hundred thirteen thousand, one hundred fifty-five".