21265129 has 2 divisors, whose sum is σ = 21265130. Its totient is φ = 21265128.

The previous prime is 21265093. The next prime is 21265151. The reversal of 21265129 is 92156212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14899600 + 6365529 = 3860^2 + 2523^2 .

It is a cyclic number.

It is not a de Polignac number, because 21265129 - 2⁷ = 21265001 is a prime.

It is a super-2 number, since 2×21265129² = 904411422773282, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21265097 and 21265106.

It is not a weakly prime, because it can be changed into another prime (21265159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10632564 + 10632565.

It is an arithmetic number, because the mean of its divisors is an integer number (10632565).

Almost surely, 2^21265129 is an apocalyptic number.

It is an amenable number.

21265129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21265129 is an equidigital number, since it uses as much as digits as its factorization.

21265129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 28.

The square root of 21265129 is about 4611.4129071251. The cubic root of 21265129 is about 277.0486301775.

It can be divided in two parts, 212 and 65129, that added together give a triangular number (65341 = T₃₆₁).

The spelling of 21265129 in words is "twenty-one million, two hundred sixty-five thousand, one hundred twenty-nine".