21042713 has 4 divisors (see below), whose sum is σ = 21091968. Its totient is φ = 20993460.

The previous prime is 21042689. The next prime is 21042731. The reversal of 21042713 is 31724012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21042713 - 2⁶ = 21042649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21042733) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23981 + ... + 24842.

It is an arithmetic number, because the mean of its divisors is an integer number (5272992).

Almost surely, 2^21042713 is an apocalyptic number.

It is an amenable number.

21042713 is a deficient number, since it is larger than the sum of its proper divisors (49255).

21042713 is an equidigital number, since it uses as much as digits as its factorization.

21042713 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49254.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21042713 is about 4587.2336979927. The cubic root of 21042713 is about 276.0793416437.

Adding to 21042713 its reverse (31724012), we get a palindrome (52766725).

It can be divided in two parts, 210 and 42713, that multiplied together give a triangular number (8969730 = T₄₂₃₅).

The spelling of 21042713 in words is "twenty-one million, forty-two thousand, seven hundred thirteen".