21155113 has 24 divisors (see below), whose sum is σ = 26776320. Its totient is φ = 16601760.

The previous prime is 21155107. The next prime is 21155117. The reversal of 21155113 is 31155112.

It is not a de Polignac number, because 21155113 - 2¹³ = 21146921 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21155117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28495 + ... + 29227.

It is an arithmetic number, because the mean of its divisors is an integer number (1115680).

Almost surely, 2^21155113 is an apocalyptic number.

It is an amenable number.

21155113 is a deficient number, since it is larger than the sum of its proper divisors (5621207).

21155113 is a wasteful number, since it uses less digits than its factorization.

21155113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 797 (or 790 counting only the distinct ones).

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

The square root of 21155113 is about 4599.4687736738. The cubic root of 21155113 is about 276.5700297970.

Subtracting 21155113 from its reverse (31155112), we obtain a palindrome (9999999).

The spelling of 21155113 in words is "twenty-one million, one hundred fifty-five thousand, one hundred thirteen".