21659801 has 2 divisors, whose sum is σ = 21659802. Its totient is φ = 21659800.

The previous prime is 21659797. The next prime is 21659843. The reversal of 21659801 is 10895612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19571776 + 2088025 = 4424^2 + 1445^2 .

It is a cyclic number.

It is not a de Polignac number, because 21659801 - 2² = 21659797 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21659851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10829900 + 10829901.

It is an arithmetic number, because the mean of its divisors is an integer number (10829901).

Almost surely, 2^21659801 is an apocalyptic number.

It is an amenable number.

21659801 is a deficient number, since it is larger than the sum of its proper divisors (1).

21659801 is an equidigital number, since it uses as much as digits as its factorization.

21659801 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 21659801 is about 4654.0091319206. The cubic root of 21659801 is about 278.7521039878.

The spelling of 21659801 in words is "twenty-one million, six hundred fifty-nine thousand, eight hundred one".