21033601 has 2 divisors, whose sum is σ = 21033602. Its totient is φ = 21033600.

The previous prime is 21033599. The next prime is 21033631. The reversal of 21033601 is 10633012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17514225 + 3519376 = 4185^2 + 1876^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033601 - 2¹ = 21033599 is a prime.

Together with 21033599, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21033631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10516800 + 10516801.

It is an arithmetic number, because the mean of its divisors is an integer number (10516801).

Almost surely, 2^21033601 is an apocalyptic number.

It is an amenable number.

21033601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033601 is an equidigital number, since it uses as much as digits as its factorization.

21033601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108, while the sum is 16.

The square root of 21033601 is about 4586.2403992813. The cubic root of 21033601 is about 276.0394862290.

Adding to 21033601 its reverse (10633012), we get a palindrome (31666613).

The spelling of 21033601 in words is "twenty-one million, thirty-three thousand, six hundred one".