21655163 has 4 divisors (see below), whose sum is σ = 21669648. Its totient is φ = 21640680.

The previous prime is 21655147. The next prime is 21655171. The reversal of 21655163 is 36155612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21655163 - 2⁴ = 21655147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21655063) 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, 4703 + ... + 8088.

It is an arithmetic number, because the mean of its divisors is an integer number (5417412).

Almost surely, 2^21655163 is an apocalyptic number.

21655163 is a deficient number, since it is larger than the sum of its proper divisors (14485).

21655163 is a wasteful number, since it uses less digits than its factorization.

21655163 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14484.

The product of its digits is 5400, while the sum is 29.

The square root of 21655163 is about 4653.5108251728. The cubic root of 21655163 is about 278.7322062281.

The spelling of 21655163 in words is "twenty-one million, six hundred fifty-five thousand, one hundred sixty-three".