21522101 has 2 divisors, whose sum is σ = 21522102. Its totient is φ = 21522100.

The previous prime is 21522077. The next prime is 21522103. The reversal of 21522101 is 10122512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20921476 + 600625 = 4574^2 + 775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21522101 - 2⁶ = 21522037 is a prime.

It is a Sophie Germain prime.

Together with 21522103, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21522103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10761050 + 10761051.

It is an arithmetic number, because the mean of its divisors is an integer number (10761051).

Almost surely, 2^21522101 is an apocalyptic number.

It is an amenable number.

21522101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21522101 is an equidigital number, since it uses as much as digits as its factorization.

21522101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21522101 is about 4639.1918477252. The cubic root of 21522101 is about 278.1601349545.

Adding to 21522101 its reverse (10122512), we get a palindrome (31644613).

The spelling of 21522101 in words is "twenty-one million, five hundred twenty-two thousand, one hundred one".