21403056 has 40 divisors (see below), whose sum is σ = 55742464. Its totient is φ = 7076160.

The previous prime is 21403049. The next prime is 21403061. The reversal of 21403056 is 65030412.

It is a happy number.

It is a super-2 number, since 2×21403056² = 916181612278272, which contains 22 as substring.

It is an unprimeable number.

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, 4341 + ... + 7851.

Almost surely, 2^21403056 is an apocalyptic number.

It is an amenable number.

21403056 is an abundant number, since it is smaller than the sum of its proper divisors (34339408).

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

21403056 is a wasteful number, since it uses less digits than its factorization.

21403056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3649 (or 3643 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21403056 is about 4626.3436967005. The cubic root of 21403056 is about 277.6463249075.

Adding to 21403056 its reverse (65030412), we get a palindrome (86433468).

The spelling of 21403056 in words is "twenty-one million, four hundred three thousand, fifty-six".