21440123 has 4 divisors (see below), whose sum is σ = 21465288. Its totient is φ = 21414960.

The previous prime is 21440119. The next prime is 21440129. The reversal of 21440123 is 32104412.

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 21440123 - 2² = 21440119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21440129) 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, 11258 + ... + 13023.

It is an arithmetic number, because the mean of its divisors is an integer number (5366322).

Almost surely, 2^21440123 is an apocalyptic number.

21440123 is a deficient number, since it is larger than the sum of its proper divisors (25165).

21440123 is an equidigital number, since it uses as much as digits as its factorization.

21440123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25164.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21440123 is about 4630.3480430741. The cubic root of 21440123 is about 277.8065135724.

Adding to 21440123 its reverse (32104412), we get a palindrome (53544535).

The spelling of 21440123 in words is "twenty-one million, four hundred forty thousand, one hundred twenty-three".