21530101 has 4 divisors (see below), whose sum is σ = 21576672. Its totient is φ = 21483532.

The previous prime is 21530099. The next prime is 21530123. The reversal of 21530101 is 10103512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21530101 - 2¹ = 21530099 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22585 + ... + 23518.

It is an arithmetic number, because the mean of its divisors is an integer number (5394168).

Almost surely, 2^21530101 is an apocalyptic number.

It is an amenable number.

21530101 is a deficient number, since it is larger than the sum of its proper divisors (46571).

21530101 is an equidigital number, since it uses as much as digits as its factorization.

21530101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46570.

The product of its (nonzero) digits is 30, while the sum is 13.

The square root of 21530101 is about 4640.0539867549. The cubic root of 21530101 is about 278.1945957384.

Adding to 21530101 its reverse (10103512), we get a palindrome (31633613).

It can be divided in two parts, 21 and 530101, that multiplied together give a triangular number (11132121 = T₄₇₁₈).

The spelling of 21530101 in words is "twenty-one million, five hundred thirty thousand, one hundred one".