21715042 has 4 divisors (see below), whose sum is σ = 32572566. Its totient is φ = 10857520.

The previous prime is 21715007. The next prime is 21715049. The reversal of 21715042 is 24051712.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 12173121 + 9541921 = 3489^2 + 3089^2 .

It is not an unprimeable number, because it can be changed into a prime (21715049) by changing a digit.

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 as a sum of consecutive naturals, namely, 5428759 + ... + 5428762.

Almost surely, 2^21715042 is an apocalyptic number.

21715042 is a deficient number, since it is larger than the sum of its proper divisors (10857524).

21715042 is a wasteful number, since it uses less digits than its factorization.

21715042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10857523.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21715042 is about 4659.9401283707. The cubic root of 21715042 is about 278.9888785964.

Adding to 21715042 its reverse (24051712), we get a palindrome (45766754).

The spelling of 21715042 in words is "twenty-one million, seven hundred fifteen thousand, forty-two".