21105144 has 64 divisors (see below), whose sum is σ = 59040000. Its totient is φ = 6985440.

The previous prime is 21105121. The next prime is 21105169. The reversal of 21105144 is 44150112.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42739 + ... + 43229.

It is an arithmetic number, because the mean of its divisors is an integer number (922500).

Almost surely, 2^21105144 is an apocalyptic number.

21105144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21105144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29520000).

21105144 is an abundant number, since it is smaller than the sum of its proper divisors (37934856).

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

21105144 is a wasteful number, since it uses less digits than its factorization.

21105144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 705 (or 695 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 21105144 is about 4594.0335218629. The cubic root of 21105144 is about 276.3521026046.

Adding to 21105144 its reverse (44150112), we get a palindrome (65255256).

The spelling of 21105144 in words is "twenty-one million, one hundred five thousand, one hundred forty-four".