21061424 has 40 divisors (see below), whose sum is σ = 44454000. Its totient is φ = 9628416.

The previous prime is 21061363. The next prime is 21061427. The reversal of 21061424 is 42416012.

It is a junction number, because it is equal to n+sod(n) for n = 21061396 and 21061405.

It is not an unprimeable number, because it can be changed into a prime (21061427) 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, 7622 + ... + 10010.

It is an arithmetic number, because the mean of its divisors is an integer number (1111350).

Almost surely, 2^21061424 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 21061424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22227000).

21061424 is an abundant number, since it is smaller than the sum of its proper divisors (23392576).

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

21061424 is a wasteful number, since it uses less digits than its factorization.

21061424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2445 (or 2439 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21061424 is about 4589.2727092645. The cubic root of 21061424 is about 276.1611465297.

Adding to 21061424 its reverse (42416012), we get a palindrome (63477436).

The spelling of 21061424 in words is "twenty-one million, sixty-one thousand, four hundred twenty-four".