21841440 has 48 divisors (see below), whose sum is σ = 68802048. Its totient is φ = 5824256.

The previous prime is 21841439. The next prime is 21841441. The reversal of 21841440 is 4414812.

It is an interprime number because it is at equal distance from previous prime (21841439) and next prime (21841441).

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21841440.

It is not an unprimeable number, because it can be changed into a prime (21841441) 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, 22272 + ... + 23231.

It is an arithmetic number, because the mean of its divisors is an integer number (1433376).

Almost surely, 2^21841440 is an apocalyptic number.

21841440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21841440 is an abundant number, since it is smaller than the sum of its proper divisors (46960608).

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

21841440 is a wasteful number, since it uses less digits than its factorization.

21841440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45521 (or 45513 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 21841440 is about 4673.4826414570. The cubic root of 21841440 is about 279.5291406003.

The spelling of 21841440 in words is "twenty-one million, eight hundred forty-one thousand, four hundred forty".