21465144 has 96 divisors (see below), whose sum is σ = 61401600. Its totient is φ = 6765120.

The previous prime is 21465137. The next prime is 21465149. The reversal of 21465144 is 44156412.

21465144 is a `hidden beast` number, since 2 + 1 + 4 + 651 + 4 + 4 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21465149) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 131607 + ... + 131769.

It is an arithmetic number, because the mean of its divisors is an integer number (639600).

Almost surely, 2^21465144 is an apocalyptic number.

21465144 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 21465144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30700800).

21465144 is an abundant number, since it is smaller than the sum of its proper divisors (39936456).

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

21465144 is a wasteful number, since it uses less digits than its factorization.

21465144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265 (or 258 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 21465144 is about 4633.0491039919. The cubic root of 21465144 is about 277.9145399202.

It can be divided in two parts, 21465 and 144, that added together give a square (21609 = 147²).

The spelling of 21465144 in words is "twenty-one million, four hundred sixty-five thousand, one hundred forty-four".