21026823 has 8 divisors (see below), whose sum is σ = 28057200. Its totient is φ = 14007168.

The previous prime is 21026821. The next prime is 21026839. The reversal of 21026823 is 32862012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21026823 - 2¹ = 21026821 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21026793 and 21026802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21026821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5263 + ... + 8351.

It is an arithmetic number, because the mean of its divisors is an integer number (3507150).

Almost surely, 2^21026823 is an apocalyptic number.

21026823 is a deficient number, since it is larger than the sum of its proper divisors (7030377).

21026823 is a wasteful number, since it uses less digits than its factorization.

21026823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5361.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21026823 is about 4585.5013902517. The cubic root of 21026823 is about 276.0098321429.

Adding to 21026823 its reverse (32862012), we get a palindrome (53888835).

The spelling of 21026823 in words is "twenty-one million, twenty-six thousand, eight hundred twenty-three".