21430656 has 192 divisors, whose sum is σ = 70171920. Its totient is φ = 6469632.

The previous prime is 21430639. The next prime is 21430667. The reversal of 21430656 is 65603412.

21430656 is a `hidden beast` number, since 2 + 1 + 4 + 3 + 0 + 656 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 404326 + ... + 404378.

It is a vampire number, since it can be written as 3456 ⋅ 6201 (with its own digits).

Almost surely, 2^21430656 is an apocalyptic number.

21430656 is a gapful number since it is divisible by the number (26) 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 21430656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35085960).

21430656 is an abundant number, since it is smaller than the sum of its proper divisors (48741264).

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

21430656 is an equidigital number, since it uses as much as digits as its factorization.

21430656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 21430656 is about 4629.3256528354. The cubic root of 21430656 is about 277.7656185729.

The spelling of 21430656 in words is "twenty-one million, four hundred thirty thousand, six hundred fifty-six".