21430242 has 24 divisors (see below), whose sum is σ = 46563660. Its totient is φ = 7123200.

The previous prime is 21430237. The next prime is 21430259. The reversal of 21430242 is 24203412.

It can be written as a sum of positive squares in 2 ways, for example, as 21427641 + 2601 = 4629^2 + 51^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5734 + ... + 8702.

Almost surely, 2^21430242 is an apocalyptic number.

21430242 is an abundant number, since it is smaller than the sum of its proper divisors (25133418).

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

21430242 is a wasteful number, since it uses less digits than its factorization.

21430242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3378 (or 3375 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21430242 is about 4629.2809376835. The cubic root of 21430242 is about 277.7638299248.

Adding to 21430242 its reverse (24203412), we get a palindrome (45633654).

The spelling of 21430242 in words is "twenty-one million, four hundred thirty thousand, two hundred forty-two".