21010020001 has 16 divisors (see below), whose sum is σ = 21268106496. Its totient is φ = 20754026496.

The previous prime is 21010019999. The next prime is 21010020007. The reversal of 21010020001 is 10002001012.

It is a cyclic number.

It is not a de Polignac number, because 21010020001 - 2¹ = 21010019999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010020007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32472660 + ... + 32473306.

It is an arithmetic number, because the mean of its divisors is an integer number (1329256656).

Almost surely, 2^21010020001 is an apocalyptic number.

It is an amenable number.

21010020001 is a deficient number, since it is larger than the sum of its proper divisors (258086495).

21010020001 is a wasteful number, since it uses less digits than its factorization.

21010020001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1728.

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 21010020001 its reverse (10002001012), we get a palindrome (31012021013).

The spelling of 21010020001 in words is "twenty-one billion, ten million, twenty thousand, one".