21042706 has 8 divisors (see below), whose sum is σ = 31584780. Its totient is φ = 10514448.

The previous prime is 21042689. The next prime is 21042731. The reversal of 21042706 is 60724012.

It can be written as a sum of positive squares in 2 ways, for example, as 17564481 + 3478225 = 4191^2 + 1865^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2220 + ... + 6856.

Almost surely, 2^21042706 is an apocalyptic number.

21042706 is a deficient number, since it is larger than the sum of its proper divisors (10542074).

21042706 is a wasteful number, since it uses less digits than its factorization.

21042706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6908.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21042706 is about 4587.2329350056. The cubic root of 21042706 is about 276.0793110305.

Adding to 21042706 its reverse (60724012), we get a palindrome (81766718).

The spelling of 21042706 in words is "twenty-one million, forty-two thousand, seven hundred six".