21211601 has 2 divisors, whose sum is σ = 21211602. Its totient is φ = 21211600.

The previous prime is 21211577. The next prime is 21211613. The reversal of 21211601 is 10611212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14326225 + 6885376 = 3785^2 + 2624^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21211601 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21211901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605800 + 10605801.

It is an arithmetic number, because the mean of its divisors is an integer number (10605801).

Almost surely, 2^21211601 is an apocalyptic number.

It is an amenable number.

21211601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211601 is an equidigital number, since it uses as much as digits as its factorization.

21211601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 14.

The square root of 21211601 is about 4605.6053890884. The cubic root of 21211601 is about 276.8159751171.

Adding to 21211601 its reverse (10611212), we get a palindrome (31822813).

It can be divided in two parts, 21211 and 601, that added together give a palindrome (21812).

The spelling of 21211601 in words is "twenty-one million, two hundred eleven thousand, six hundred one".