21001201 has 4 divisors (see below), whose sum is σ = 22616692. Its totient is φ = 19385712.

The previous prime is 21001187. The next prime is 21001247. The reversal of 21001201 is 10210012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14447601 + 6553600 = 3801^2 + 2560^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001201 - 2⁹ = 21000689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 807726 + ... + 807751.

It is an arithmetic number, because the mean of its divisors is an integer number (5654173).

Almost surely, 2^21001201 is an apocalyptic number.

It is an amenable number.

21001201 is a deficient number, since it is larger than the sum of its proper divisors (1615491).

21001201 is a wasteful number, since it uses less digits than its factorization.

21001201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1615490.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21001201 is about 4582.7067329254. The cubic root of 21001201 is about 275.8976770108.

Adding to 21001201 its reverse (10210012), we get a palindrome (31211213).

The spelling of 21001201 in words is "twenty-one million, one thousand, two hundred one".