21275129 has 2 divisors, whose sum is σ = 21275130. Its totient is φ = 21275128.

The previous prime is 21275123. The next prime is 21275171. The reversal of 21275129 is 92157212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10725625 + 10549504 = 3275^2 + 3248^2 .

It is a cyclic number.

It is not a de Polignac number, because 21275129 - 2⁸ = 21274873 is a prime.

It is a super-2 number, since 2×21275129² = 905262227933282, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21275123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10637564 + 10637565.

It is an arithmetic number, because the mean of its divisors is an integer number (10637565).

Almost surely, 2^21275129 is an apocalyptic number.

It is an amenable number.

21275129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21275129 is an equidigital number, since it uses as much as digits as its factorization.

21275129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 29.

The square root of 21275129 is about 4612.4970460695. The cubic root of 21275129 is about 277.0920510621.

The spelling of 21275129 in words is "twenty-one million, two hundred seventy-five thousand, one hundred twenty-nine".