21164441 has 2 divisors, whose sum is σ = 21164442. Its totient is φ = 21164440.

The previous prime is 21164431. The next prime is 21164447. The reversal of 21164441 is 14446112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20894041 + 270400 = 4571^2 + 520^2 .

It is a cyclic number.

It is not a de Polignac number, because 21164441 - 2²² = 16970137 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21164447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582220 + 10582221.

It is an arithmetic number, because the mean of its divisors is an integer number (10582221).

Almost surely, 2^21164441 is an apocalyptic number.

It is an amenable number.

21164441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21164441 is an equidigital number, since it uses as much as digits as its factorization.

21164441 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 23.

The square root of 21164441 is about 4600.4826920661. The cubic root of 21164441 is about 276.6106734963.

The spelling of 21164441 in words is "twenty-one million, one hundred sixty-four thousand, four hundred forty-one".