21156135 has 64 divisors (see below), whose sum is σ = 45480960. Its totient is φ = 8110080.

The previous prime is 21156131. The next prime is 21156151. The reversal of 21156135 is 53165112.

It is not a de Polignac number, because 21156135 - 2² = 21156131 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156131) 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 63 ways as a sum of consecutive naturals, for example, 14311 + ... + 15719.

It is an arithmetic number, because the mean of its divisors is an integer number (710640).

Almost surely, 2^21156135 is an apocalyptic number.

21156135 is an abundant number, since it is smaller than the sum of its proper divisors (24324825).

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

21156135 is a wasteful number, since it uses less digits than its factorization.

21156135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1448.

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

The square root of 21156135 is about 4599.5798721188. The cubic root of 21156135 is about 276.5744834094.

The spelling of 21156135 in words is "twenty-one million, one hundred fifty-six thousand, one hundred thirty-five".