21658201 has 2 divisors, whose sum is σ = 21658202. Its totient is φ = 21658200.

The previous prime is 21658183. The next prime is 21658207. The reversal of 21658201 is 10285612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16818201 + 4840000 = 4101^2 + 2200^2 .

It is a cyclic number.

It is not a de Polignac number, because 21658201 - 2⁹ = 21657689 is a prime.

It is not a weakly prime, because it can be changed into another prime (21658207) 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, 10829100 + 10829101.

It is an arithmetic number, because the mean of its divisors is an integer number (10829101).

Almost surely, 2^21658201 is an apocalyptic number.

It is an amenable number.

21658201 is a deficient number, since it is larger than the sum of its proper divisors (1).

21658201 is an equidigital number, since it uses as much as digits as its factorization.

21658201 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 21658201 is about 4653.8372339393. The cubic root of 21658201 is about 278.7452400536.

The spelling of 21658201 in words is "twenty-one million, six hundred fifty-eight thousand, two hundred one".