21101000021001 has 12 divisors (see below), whose sum is σ = 32272117679412. Its totient is φ = 13239843150336.

The previous prime is 21101000020981. The next prime is 21101000021009. The reversal of 21101000021001 is 10012000010112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 10976996054025 + 10124003966976 = 3313155^2 + 3181824^2 .

It is not a de Polignac number, because 21101000021001 - 2³⁰ = 21099926279177 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 (21101000021009) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68957516256 + ... + 68957516561.

It is an arithmetic number, because the mean of its divisors is an integer number (2689343139951).

Almost surely, 2^{21101000021001} is an apocalyptic number.

It is an amenable number.

21101000021001 is a deficient number, since it is larger than the sum of its proper divisors (11171117658411).

21101000021001 is a wasteful number, since it uses less digits than its factorization.

21101000021001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137915032840 (or 137915032837 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21101000021001 its reverse (10012000010112), we get a palindrome (31113000031113).

The spelling of 21101000021001 in words is "twenty-one trillion, one hundred one billion, twenty-one thousand, one".