21155136 has 28 divisors (see below), whose sum is σ = 55973472. Its totient is φ = 7051648.

The previous prime is 21155131. The next prime is 21155149. The reversal of 21155136 is 63155112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54900 + ... + 55283.

Almost surely, 2^21155136 is an apocalyptic number.

It is an amenable number.

21155136 is an abundant number, since it is smaller than the sum of its proper divisors (34818336).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21155136 is a wasteful number, since it uses less digits than its factorization.

21155136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110198 (or 110188 counting only the distinct ones).

The product of its digits is 900, while the sum is 24.

The square root of 21155136 is about 4599.4712739618. The cubic root of 21155136 is about 276.5701300267.

Subtracting from 21155136 its sum of digits (24), we obtain a palindrome (21155112).

The spelling of 21155136 in words is "twenty-one million, one hundred fifty-five thousand, one hundred thirty-six".