21010021001 has 16 divisors (see below), whose sum is σ = 22571539200. Its totient is φ = 19497403728.

The previous prime is 21010020991. The next prime is 21010021027. The reversal of 21010021001 is 10012001012.

It is a cyclic number.

It is not a de Polignac number, because 21010021001 - 2²² = 21005826697 is a prime.

It is a super-2 number, since 2×21010021001² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21010021001.

It is not an unprimeable number, because it can be changed into a prime (21010021091) 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, 181766 + ... + 273968.

It is an arithmetic number, because the mean of its divisors is an integer number (1410721200).

Almost surely, 2^21010021001 is an apocalyptic number.

It is an amenable number.

21010021001 is a deficient number, since it is larger than the sum of its proper divisors (1561518199).

21010021001 is a wasteful number, since it uses less digits than its factorization.

21010021001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92468.

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21010021001 its reverse (10012001012), we get a palindrome (31022022013).

The spelling of 21010021001 in words is "twenty-one billion, ten million, twenty-one thousand, one".