21001201021 has 8 divisors (see below), whose sum is σ = 21200830200. Its totient is φ = 20801698560.

The previous prime is 21001200991. The next prime is 21001201127. The reversal of 21001201021 is 12010210012.

It can be written as a sum of positive squares in 4 ways, for example, as 12930873796 + 8070327225 = 113714^2 + 89835^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001201021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001200989 and 21001201007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001201321) 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, 319761 + ... + 379801.

It is an arithmetic number, because the mean of its divisors is an integer number (2650103775).

Almost surely, 2^21001201021 is an apocalyptic number.

It is an amenable number.

21001201021 is a deficient number, since it is larger than the sum of its proper divisors (199629179).

21001201021 is a wasteful number, since it uses less digits than its factorization.

21001201021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63359.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21001201021 its reverse (12010210012), we get a palindrome (33011411033).

The spelling of 21001201021 in words is "twenty-one billion, one million, two hundred one thousand, twenty-one".