21550144 has 56 divisors (see below), whose sum is σ = 53327808. Its totient is φ = 8394240.

The previous prime is 21550129. The next prime is 21550147. The reversal of 21550144 is 44105512.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21550147) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2742 + ... + 7114.

Almost surely, 2^21550144 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21550144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26663904).

21550144 is an abundant number, since it is smaller than the sum of its proper divisors (31777664).

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

21550144 is a wasteful number, since it uses less digits than its factorization.

21550144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4403 (or 4393 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 22.

The square root of 21550144 is about 4642.2132652432. The cubic root of 21550144 is about 278.2808954564.

Adding to 21550144 its reverse (44105512), we get a palindrome (65655656).

The spelling of 21550144 in words is "twenty-one million, five hundred fifty thousand, one hundred forty-four".