21001056101 has 4 divisors (see below), whose sum is σ = 21217561932. Its totient is φ = 20784550272.

The previous prime is 21001056091. The next prime is 21001056119. The reversal of 21001056101 is 10165010012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7212425476 + 13788630625 = 84926^2 + 117425^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001056101 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001056101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001050101) 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 3 ways as a sum of consecutive naturals, for example, 108252770 + ... + 108252963.

It is an arithmetic number, because the mean of its divisors is an integer number (5304390483).

Almost surely, 2^21001056101 is an apocalyptic number.

It is an amenable number.

21001056101 is a deficient number, since it is larger than the sum of its proper divisors (216505831).

21001056101 is an equidigital number, since it uses as much as digits as its factorization.

21001056101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216505830.

The product of its (nonzero) digits is 60, while the sum is 17.

Adding to 21001056101 its reverse (10165010012), we get a palindrome (31166066113).

The spelling of 21001056101 in words is "twenty-one billion, one million, fifty-six thousand, one hundred one".