21802541 has 2 divisors, whose sum is σ = 21802542. Its totient is φ = 21802540.

The previous prime is 21802531. The next prime is 21802549. The reversal of 21802541 is 14520812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21353641 + 448900 = 4621^2 + 670^2 .

It is a cyclic number.

It is not a de Polignac number, because 21802541 - 2¹⁰ = 21801517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21802549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10901270 + 10901271.

It is an arithmetic number, because the mean of its divisors is an integer number (10901271).

Almost surely, 2^21802541 is an apocalyptic number.

It is an amenable number.

21802541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21802541 is an equidigital number, since it uses as much as digits as its factorization.

21802541 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21802541 is about 4669.3191152458. The cubic root of 21802541 is about 279.3630974348.

The spelling of 21802541 in words is "twenty-one million, eight hundred two thousand, five hundred forty-one".