21201001101001 has 4 divisors (see below), whose sum is σ = 21202868548372. Its totient is φ = 21199133653632.

The previous prime is 21201001100969. The next prime is 21201001101011. The reversal of 21201001101001 is 10010110010212.

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 5503152974400 + 15697848126601 = 2345880^2 + 3962051^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201001101001 - 2⁵ = 21201001100969 is a prime.

It is a super-2 number, since 2×21201001101001² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201001101011) 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, 933706656 + ... + 933729361.

It is an arithmetic number, because the mean of its divisors is an integer number (5300717137093).

Almost surely, 2^{21201001101001} is an apocalyptic number.

It is an amenable number.

21201001101001 is a deficient number, since it is larger than the sum of its proper divisors (1867447371).

21201001101001 is a wasteful number, since it uses less digits than its factorization.

21201001101001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1867447370.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21201001101001 its reverse (10010110010212), we get a palindrome (31211111111213).

The spelling of 21201001101001 in words is "twenty-one trillion, two hundred one billion, one million, one hundred one thousand, one".