21201601 has 8 divisors (see below), whose sum is σ = 22506120. Its totient is φ = 19903488.

The previous prime is 21201599. The next prime is 21201611. The reversal of 21201601 is 10610212.

It can be written as a sum of positive squares in 4 ways, for example, as 15800625 + 5400976 = 3975^2 + 2324^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21201601 - 2¹ = 21201599 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6405 + ... + 9133.

It is an arithmetic number, because the mean of its divisors is an integer number (2813265).

Almost surely, 2^21201601 is an apocalyptic number.

It is an amenable number.

21201601 is a deficient number, since it is larger than the sum of its proper divisors (1304519).

21201601 is a wasteful number, since it uses less digits than its factorization.

21201601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3203.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 21201601 is about 4604.5196274964. The cubic root of 21201601 is about 276.7724675593.

Adding to 21201601 its reverse (10610212), we get a palindrome (31811813).

It can be divided in two parts, 2120 and 1601, that added together give a square (3721 = 61²).

The spelling of 21201601 in words is "twenty-one million, two hundred one thousand, six hundred one".