21020101 has 4 divisors (see below), whose sum is σ = 21042304. Its totient is φ = 20997900.

The previous prime is 21020093. The next prime is 21020117. The reversal of 21020101 is 10102012.

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 21020101 - 2³ = 21020093 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 (21020161) 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, 9615 + ... + 11596.

It is an arithmetic number, because the mean of its divisors is an integer number (5260576).

Almost surely, 2^21020101 is an apocalyptic number.

It is an amenable number.

21020101 is a deficient number, since it is larger than the sum of its proper divisors (22203).

21020101 is an equidigital number, since it uses as much as digits as its factorization.

21020101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22202.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21020101 is about 4584.7683692854. The cubic root of 21020101 is about 275.9804167650.

Adding to 21020101 its reverse (10102012), we get a palindrome (31122113).

The spelling of 21020101 in words is "twenty-one million, twenty thousand, one hundred one".