21002121201001 has 8 divisors (see below), whose sum is σ = 21531058857000. Its totient is φ = 20473978344960.

The previous prime is 21002121200939. The next prime is 21002121201031. The reversal of 21002121201001 is 10010212120012.

It can be written as a sum of positive squares in 4 ways, for example, as 609490928601 + 20392630272400 = 780699^2 + 4515820^2 .

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 21002121201001 - 2¹³ = 21002121192809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21002121201031) 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, 198646476 + ... + 198752173.

It is an arithmetic number, because the mean of its divisors is an integer number (2691382357125).

Almost surely, 2^{21002121201001} is an apocalyptic number.

It is an amenable number.

21002121201001 is a deficient number, since it is larger than the sum of its proper divisors (528937655999).

21002121201001 is a wasteful number, since it uses less digits than its factorization.

21002121201001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397399979.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21002121201001 its reverse (10010212120012), we get a palindrome (31012333321013).

The spelling of 21002121201001 in words is "twenty-one trillion, two billion, one hundred twenty-one million, two hundred one thousand, one".