21163155 has 16 divisors (see below), whose sum is σ = 36466080. Its totient is φ = 10418688.

The previous prime is 21163141. The next prime is 21163159. The reversal of 21163155 is 55136112.

It is not a de Polignac number, because 21163155 - 2⁴ = 21163139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21163159) 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, 54070 + ... + 54459.

It is an arithmetic number, because the mean of its divisors is an integer number (2279130).

Almost surely, 2^21163155 is an apocalyptic number.

21163155 is a deficient number, since it is larger than the sum of its proper divisors (15302925).

21163155 is a wasteful number, since it uses less digits than its factorization.

21163155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108550.

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

The square root of 21163155 is about 4600.3429220005. The cubic root of 21163155 is about 276.6050708830.

Adding to 21163155 its reverse (55136112), we get a palindrome (76299267).

The spelling of 21163155 in words is "twenty-one million, one hundred sixty-three thousand, one hundred fifty-five".