21143155 has 16 divisors (see below), whose sum is σ = 29307744. Its totient is φ = 14471680.

The previous prime is 21143137. The next prime is 21143179. The reversal of 21143155 is 55134112.

It is a happy number.

It is not a de Polignac number, because 21143155 - 2⁹ = 21142643 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10372 + ... + 12241.

It is an arithmetic number, because the mean of its divisors is an integer number (1831734).

Almost surely, 2^21143155 is an apocalyptic number.

21143155 is a deficient number, since it is larger than the sum of its proper divisors (8164589).

21143155 is a wasteful number, since it uses less digits than its factorization.

21143155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22646.

The product of its digits is 600, while the sum is 22.

The square root of 21143155 is about 4598.1686571939. The cubic root of 21143155 is about 276.5179092568.

Adding to 21143155 its reverse (55134112), we get a palindrome (76277267).

The spelling of 21143155 in words is "twenty-one million, one hundred forty-three thousand, one hundred fifty-five".