21413440 has 56 divisors (see below), whose sum is σ = 51873912. Its totient is φ = 8417280.

The previous prime is 21413423. The next prime is 21413443. The reversal of 21413440 is 4431412.

It can be written as a sum of positive squares in 4 ways, for example, as 179776 + 21233664 = 424^2 + 4608^2 .

It is not an unprimeable number, because it can be changed into a prime (21413443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18972 + ... + 20068.

Almost surely, 2^21413440 is an apocalyptic number.

21413440 is a gapful number since it is divisible by the number (20) 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 21413440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25936956).

21413440 is an abundant number, since it is smaller than the sum of its proper divisors (30460472).

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

21413440 is a wasteful number, since it uses less digits than its factorization.

21413440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1175 (or 1165 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21413440 is about 4627.4658291553. The cubic root of 21413440 is about 277.6912190153.

Adding to 21413440 its reverse (4431412), we get a palindrome (25844852).

The spelling of 21413440 in words is "twenty-one million, four hundred thirteen thousand, four hundred forty".