21020001002001 has 24 divisors (see below), whose sum is σ = 30533844781440. Its totient is φ = 13934143908000.

The previous prime is 21020001001973. The next prime is 21020001002027. The reversal of 21020001002001 is 10020010002012.

It is not a de Polignac number, because 21020001002001 - 2³⁸ = 20745123095057 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21020001002041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12085326 + ... + 13714776.

It is an arithmetic number, because the mean of its divisors is an integer number (1272243532560).

Almost surely, 2^{21020001002001} is an apocalyptic number.

It is an amenable number.

21020001002001 is a deficient number, since it is larger than the sum of its proper divisors (9513843779439).

21020001002001 is a wasteful number, since it uses less digits than its factorization.

21020001002001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1637557 (or 1637554 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21020001002001 its reverse (10020010002012), we get a palindrome (31040011004013).

The spelling of 21020001002001 in words is "twenty-one trillion, twenty billion, one million, two thousand, one".