21123144 has 48 divisors (see below), whose sum is σ = 65382720. Its totient is φ = 6035040.

The previous prime is 21123143. The next prime is 21123149. The reversal of 21123144 is 44132112.

21123144 = T₁₂₇ + T₁₂₈ + ... + T₅₀₄.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21123143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20452 + ... + 21459.

It is an arithmetic number, because the mean of its divisors is an integer number (1362140).

Almost surely, 2^21123144 is an apocalyptic number.

21123144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21123144 is an abundant number, since it is smaller than the sum of its proper divisors (44259576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123144 is a wasteful number, since it uses less digits than its factorization.

21123144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41930 (or 41923 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 21123144 is about 4595.9921670952. The cubic root of 21123144 is about 276.4306446630.

Adding to 21123144 its reverse (44132112), we get a palindrome (65255256).

The spelling of 21123144 in words is "twenty-one million, one hundred twenty-three thousand, one hundred forty-four".