21143823 has 16 divisors (see below), whose sum is σ = 29018976. Its totient is φ = 13685760.

The previous prime is 21143807. The next prime is 21143839. The reversal of 21143823 is 32834112.

It is an interprime number because it is at equal distance from previous prime (21143807) and next prime (21143839).

It is not a de Polignac number, because 21143823 - 2⁴ = 21143807 is a prime.

It is a super-2 number, since 2×21143823² = 894122502110658, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21143793 and 21143802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21143893) 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, 48615 + ... + 49047.

It is an arithmetic number, because the mean of its divisors is an integer number (1813686).

Almost surely, 2^21143823 is an apocalyptic number.

21143823 is a deficient number, since it is larger than the sum of its proper divisors (7875153).

21143823 is a wasteful number, since it uses less digits than its factorization.

21143823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874.

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

The square root of 21143823 is about 4598.2412942341. The cubic root of 21143823 is about 276.5208213422.

Adding to 21143823 its reverse (32834112), we get a palindrome (53977935).

The spelling of 21143823 in words is "twenty-one million, one hundred forty-three thousand, eight hundred twenty-three".