21742841 has 4 divisors (see below), whose sum is σ = 21967092. Its totient is φ = 21518592.

The previous prime is 21742829. The next prime is 21742913. The reversal of 21742841 is 14824712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16810000 + 4932841 = 4100^2 + 2221^2 .

It is a cyclic number.

It is not a de Polignac number, because 21742841 - 2¹⁰ = 21741817 is a prime.

It is a super-2 number, since 2×21742841² = 945502269502562, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21744841) 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, 111980 + ... + 112173.

It is an arithmetic number, because the mean of its divisors is an integer number (5491773).

Almost surely, 2^21742841 is an apocalyptic number.

It is an amenable number.

21742841 is a deficient number, since it is larger than the sum of its proper divisors (224251).

21742841 is an equidigital number, since it uses as much as digits as its factorization.

21742841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224250.

The product of its digits is 3584, while the sum is 29.

The square root of 21742841 is about 4662.9219380127. The cubic root of 21742841 is about 279.1078791289.

The spelling of 21742841 in words is "twenty-one million, seven hundred forty-two thousand, eight hundred forty-one".