21255210101 has 2 divisors, whose sum is σ = 21255210102. Its totient is φ = 21255210100.

The previous prime is 21255210071. The next prime is 21255210121. The reversal of 21255210101 is 10101255212.

It is an a-pointer prime, because the next prime (21255210121) can be obtained adding 21255210101 to its sum of digits (20).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20657163076 + 598047025 = 143726^2 + 24455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255210101 - 2¹⁴ = 21255193717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255210121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627605050 + 10627605051.

It is an arithmetic number, because the mean of its divisors is an integer number (10627605051).

Almost surely, 2^21255210101 is an apocalyptic number.

It is an amenable number.

21255210101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255210101 is an equidigital number, since it uses as much as digits as its factorization.

21255210101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 200, while the sum is 20.

Adding to 21255210101 its reverse (10101255212), we get a palindrome (31356465313).

The spelling of 21255210101 in words is "twenty-one billion, two hundred fifty-five million, two hundred ten thousand, one hundred one".