21021101 has 2 divisors, whose sum is σ = 21021102. Its totient is φ = 21021100.

The previous prime is 21021083. The next prime is 21021107. The reversal of 21021101 is 10112012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17222500 + 3798601 = 4150^2 + 1949^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510550 + 10510551.

It is an arithmetic number, because the mean of its divisors is an integer number (10510551).

Almost surely, 2^21021101 is an apocalyptic number.

It is an amenable number.

21021101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021101 is an equidigital number, since it uses as much as digits as its factorization.

21021101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4, while the sum is 8.

The square root of 21021101 is about 4584.8774247519. The cubic root of 21021101 is about 275.9847931480.

Adding to 21021101 its reverse (10112012), we get a palindrome (31133113).

The spelling of 21021101 in words is "twenty-one million, twenty-one thousand, one hundred one".