21124742 has 4 divisors (see below), whose sum is σ = 31687116. Its totient is φ = 10562370.

The previous prime is 21124711. The next prime is 21124759. The reversal of 21124742 is 24742112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5281184 + ... + 5281187.

It is an arithmetic number, because the mean of its divisors is an integer number (7921779).

Almost surely, 2^21124742 is an apocalyptic number.

21124742 is a deficient number, since it is larger than the sum of its proper divisors (10562374).

21124742 is a wasteful number, since it uses less digits than its factorization.

21124742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10562373.

The product of its digits is 896, while the sum is 23.

The square root of 21124742 is about 4596.1660109269. The cubic root of 21124742 is about 276.4376152956.

Adding to 21124742 its reverse (24742112), we get a palindrome (45866854).

The spelling of 21124742 in words is "twenty-one million, one hundred twenty-four thousand, seven hundred forty-two".