21424747 has 8 divisors (see below), whose sum is σ = 21811680. Its totient is φ = 21040320.

The previous prime is 21424699. The next prime is 21424759. The reversal of 21424747 is 74742412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21424747 - 2⁷ = 21424619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21424787) 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, 26079 + ... + 26887.

It is an arithmetic number, because the mean of its divisors is an integer number (2726460).

Almost surely, 2^21424747 is an apocalyptic number.

21424747 is a deficient number, since it is larger than the sum of its proper divisors (386933).

21424747 is an equidigital number, since it uses as much as digits as its factorization.

21424747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1253.

The product of its digits is 12544, while the sum is 31.

The square root of 21424747 is about 4628.6873949317. The cubic root of 21424747 is about 277.7400871113.

It can be divided in two parts, 2142 and 4747, that added together give a square (6889 = 83²).

The spelling of 21424747 in words is "twenty-one million, four hundred twenty-four thousand, seven hundred forty-seven".