21130101 has 6 divisors (see below), whose sum is σ = 30521270. Its totient is φ = 14086728.

The previous prime is 21130079. The next prime is 21130111. The reversal of 21130101 is 10103112.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 62001 = 4590^2 + 249^2 .

It is not a de Polignac number, because 21130101 - 2⁶ = 21130037 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 2347789 = 21130101 / (2 + 1 + 1 + 3 + 0 + 1 + 0 + 1).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1173886 + ... + 1173903.

Almost surely, 2^21130101 is an apocalyptic number.

It is an amenable number.

21130101 is a deficient number, since it is larger than the sum of its proper divisors (9391169).

21130101 is a wasteful number, since it uses less digits than its factorization.

21130101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2347795 (or 2347792 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 9.

The square root of 21130101 is about 4596.7489598628. The cubic root of 21130101 is about 276.4609892131.

Adding to 21130101 its reverse (10103112), we get a palindrome (31233213).

The spelling of 21130101 in words is "twenty-one million, one hundred thirty thousand, one hundred one".