21545441 has 2 divisors, whose sum is σ = 21545442. Its totient is φ = 21545440.

The previous prime is 21545429. The next prime is 21545471. The reversal of 21545441 is 14454512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12931216 + 8614225 = 3596^2 + 2935^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545441 - 2²² = 17351137 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21545441.

It is not a weakly prime, because it can be changed into another prime (21545471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772720 + 10772721.

It is an arithmetic number, because the mean of its divisors is an integer number (10772721).

Almost surely, 2^21545441 is an apocalyptic number.

It is an amenable number.

21545441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545441 is an equidigital number, since it uses as much as digits as its factorization.

21545441 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3200, while the sum is 26.

The square root of 21545441 is about 4641.7066904319. The cubic root of 21545441 is about 278.2606504212.

Adding to 21545441 its reverse (14454512), we get a palindrome (35999953).

The spelling of 21545441 in words is "twenty-one million, five hundred forty-five thousand, four hundred forty-one".