21100129 has 2 divisors, whose sum is σ = 21100130. Its totient is φ = 21100128.

The previous prime is 21100103. The next prime is 21100141. The reversal of 21100129 is 92100112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11209104 + 9891025 = 3348^2 + 3145^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100129 - 2⁵ = 21100097 is a prime.

It is not a weakly prime, because it can be changed into another prime (21100159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550064 + 10550065.

It is an arithmetic number, because the mean of its divisors is an integer number (10550065).

Almost surely, 2^21100129 is an apocalyptic number.

It is an amenable number.

21100129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100129 is an equidigital number, since it uses as much as digits as its factorization.

21100129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21100129 is about 4593.4876727820. The cubic root of 21100129 is about 276.3302119606.

The spelling of 21100129 in words is "twenty-one million, one hundred thousand, one hundred twenty-nine".