21442541 has 4 divisors (see below), whose sum is σ = 21632412. Its totient is φ = 21252672.

The previous prime is 21442501. The next prime is 21442543. The reversal of 21442541 is 14524412.

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 7678441 + 13764100 = 2771^2 + 3710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21442541 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442543) 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, 94766 + ... + 94991.

It is an arithmetic number, because the mean of its divisors is an integer number (5408103).

Almost surely, 2^21442541 is an apocalyptic number.

It is an amenable number.

21442541 is a deficient number, since it is larger than the sum of its proper divisors (189871).

21442541 is a wasteful number, since it uses less digits than its factorization.

21442541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189870.

The product of its digits is 1280, while the sum is 23.

The square root of 21442541 is about 4630.6091391954. The cubic root of 21442541 is about 277.8169567789.

Adding to 21442541 its reverse (14524412), we get a palindrome (35966953).

The spelling of 21442541 in words is "twenty-one million, four hundred forty-two thousand, five hundred forty-one".