21865033 has 4 divisors (see below), whose sum is σ = 22164628. Its totient is φ = 21565440.

The previous prime is 21865007. The next prime is 21865037. The reversal of 21865033 is 33056812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16426809 + 5438224 = 4053^2 + 2332^2 .

It is a cyclic number.

It is not a de Polignac number, because 21865033 - 2⁵ = 21865001 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21864992 and 21865010.

It is not an unprimeable number, because it can be changed into a prime (21865037) 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 3 ways as a sum of consecutive naturals, for example, 149688 + ... + 149833.

It is an arithmetic number, because the mean of its divisors is an integer number (5541157).

Almost surely, 2^21865033 is an apocalyptic number.

It is an amenable number.

21865033 is a deficient number, since it is larger than the sum of its proper divisors (299595).

21865033 is an equidigital number, since it uses as much as digits as its factorization.

21865033 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 299594.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21865033 is about 4676.0060949490. The cubic root of 21865033 is about 279.6297529811.

The spelling of 21865033 in words is "twenty-one million, eight hundred sixty-five thousand, thirty-three".