21423144 has 32 divisors (see below), whose sum is σ = 53676000. Its totient is φ = 7125312.

The previous prime is 21423119. The next prime is 21423161. The reversal of 21423144 is 44132412.

It is a super-4 number, since 4×21423144⁴ (a number of 30 digits) contains 4444 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21423144.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16387 + ... + 17645.

It is an arithmetic number, because the mean of its divisors is an integer number (1677375).

Almost surely, 2^21423144 is an apocalyptic number.

21423144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21423144 is an abundant number, since it is smaller than the sum of its proper divisors (32252856).

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

21423144 is a wasteful number, since it uses less digits than its factorization.

21423144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1977 (or 1973 counting only the distinct ones).

The product of its digits is 768, while the sum is 21.

The square root of 21423144 is about 4628.5142324508. The cubic root of 21423144 is about 277.7331600989.

Adding to 21423144 its reverse (44132412), we get a palindrome (65555556).

The spelling of 21423144 in words is "twenty-one million, four hundred twenty-three thousand, one hundred forty-four".