21155344 has 80 divisors (see below), whose sum is σ = 50996736. Its totient is φ = 8294400.

The previous prime is 21155339. The next prime is 21155363. The reversal of 21155344 is 44355112.

21155344 = T₂₉₇ + T₂₉₈ + ... + T₅₃₄.

It is a happy number.

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, 77929 + ... + 78199.

Almost surely, 2^21155344 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 21155344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25498368).

21155344 is an abundant number, since it is smaller than the sum of its proper divisors (29841392).

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

21155344 is a wasteful number, since it uses less digits than its factorization.

21155344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344 (or 338 counting only the distinct ones).

The product of its digits is 2400, while the sum is 25.

The square root of 21155344 is about 4599.4938852008. The cubic root of 21155344 is about 276.5710364480.

It can be divided in two parts, 211 and 55344, that added together give a palindrome (55555).

The spelling of 21155344 in words is "twenty-one million, one hundred fifty-five thousand, three hundred forty-four".