21706242 has 16 divisors (see below), whose sum is σ = 43458240. Its totient is φ = 7227792.

The previous prime is 21706241. The next prime is 21706253. The reversal of 21706242 is 24260712.

It is not an unprimeable number, because it can be changed into a prime (21706241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9684 + ... + 11712.

It is an arithmetic number, because the mean of its divisors is an integer number (2716140).

Almost surely, 2^21706242 is an apocalyptic number.

21706242 is an abundant number, since it is smaller than the sum of its proper divisors (21751998).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21706242 is a wasteful number, since it uses less digits than its factorization.

21706242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3817.

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 21706242 is about 4658.9958145506. The cubic root of 21706242 is about 278.9511868457.

Adding to 21706242 its reverse (24260712), we get a palindrome (45966954).

The spelling of 21706242 in words is "twenty-one million, seven hundred six thousand, two hundred forty-two".