21111423 has 16 divisors (see below), whose sum is σ = 29247840. Its totient is φ = 13533696.

The previous prime is 21111397. The next prime is 21111457. The reversal of 21111423 is 32411112.

It is not a de Polignac number, because 21111423 - 2²¹ = 19014271 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111463) 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, 8811 + ... + 10947.

It is an arithmetic number, because the mean of its divisors is an integer number (1827990).

Almost surely, 2^21111423 is an apocalyptic number.

21111423 is a deficient number, since it is larger than the sum of its proper divisors (8136417).

21111423 is a wasteful number, since it uses less digits than its factorization.

21111423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2266.

The product of its digits is 48, while the sum is 15.

The square root of 21111423 is about 4594.7168574353. The cubic root of 21111423 is about 276.3795057628.

Adding to 21111423 its reverse (32411112), we get a palindrome (53522535).

The spelling of 21111423 in words is "twenty-one million, one hundred eleven thousand, four hundred twenty-three".