21175129 has 2 divisors, whose sum is σ = 21175130. Its totient is φ = 21175128.

The previous prime is 21175117. The next prime is 21175151. The reversal of 21175129 is 92157112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21160000 + 15129 = 4600^2 + 123^2 .

It is a cyclic number.

It is not a de Polignac number, because 21175129 - 2⁵ = 21175097 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21175097 and 21175106.

It is not a weakly prime, because it can be changed into another prime (21175169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587564 + 10587565.

It is an arithmetic number, because the mean of its divisors is an integer number (10587565).

Almost surely, 2^21175129 is an apocalyptic number.

It is an amenable number.

21175129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21175129 is an equidigital number, since it uses as much as digits as its factorization.

21175129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1260, while the sum is 28.

The square root of 21175129 is about 4601.6441626879. The cubic root of 21175129 is about 276.6572282711.

The spelling of 21175129 in words is "twenty-one million, one hundred seventy-five thousand, one hundred twenty-nine".