21242734 has 8 divisors (see below), whose sum is σ = 32055408. Its totient is φ = 10557600.

The previous prime is 21242729. The next prime is 21242747. The reversal of 21242734 is 43724212.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21242699 and 21242708.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 31467 + ... + 32134.

It is an arithmetic number, because the mean of its divisors is an integer number (4006926).

Almost surely, 2^21242734 is an apocalyptic number.

21242734 is a deficient number, since it is larger than the sum of its proper divisors (10812674).

21242734 is a wasteful number, since it uses less digits than its factorization.

21242734 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63770.

The product of its digits is 2688, while the sum is 25.

The square root of 21242734 is about 4608.9840529123. The cubic root of 21242734 is about 276.9513397040.

Adding to 21242734 its reverse (43724212), we get a palindrome (64966946).

The spelling of 21242734 in words is "twenty-one million, two hundred forty-two thousand, seven hundred thirty-four".