21001102101 has 24 divisors (see below), whose sum is σ = 34757648640. Its totient is φ = 11969765856.

The previous prime is 21001102091. The next prime is 21001102121. The reversal of 21001102101 is 10120110012.

It is a happy number.

It is not a de Polignac number, because 21001102101 - 2¹¹ = 21001100053 is a prime.

It is a super-2 number, since 2×21001102101² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001102121) 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 23 ways as a sum of consecutive naturals, for example, 403965 + ... + 452978.

It is an arithmetic number, because the mean of its divisors is an integer number (1448235360).

Almost surely, 2^21001102101 is an apocalyptic number.

21001102101 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21001102101 is a deficient number, since it is larger than the sum of its proper divisors (13756546539).

21001102101 is a wasteful number, since it uses less digits than its factorization.

21001102101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 857345 (or 857342 counting only the distinct ones).

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

Adding to 21001102101 its reverse (10120110012), we get a palindrome (31121212113).

The spelling of 21001102101 in words is "twenty-one billion, one million, one hundred two thousand, one hundred one".