21320801 has 2 divisors, whose sum is σ = 21320802. Its totient is φ = 21320800.

The previous prime is 21320749. The next prime is 21320813. The reversal of 21320801 is 10802312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21160000 + 160801 = 4600^2 + 401^2 .

It is a cyclic number.

It is not a de Polignac number, because 21320801 - 2¹⁰ = 21319777 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 21320801.

It is not a weakly prime, because it can be changed into another prime (21320821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660400 + 10660401.

It is an arithmetic number, because the mean of its divisors is an integer number (10660401).

Almost surely, 2^21320801 is an apocalyptic number.

It is an amenable number.

21320801 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320801 is an equidigital number, since it uses as much as digits as its factorization.

21320801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21320801 is about 4617.4452893348. The cubic root of 21320801 is about 277.2901901358.

The spelling of 21320801 in words is "twenty-one million, three hundred twenty thousand, eight hundred one".