21431129 has 2 divisors, whose sum is σ = 21431130. Its totient is φ = 21431128.

The previous prime is 21431119. The next prime is 21431131. The reversal of 21431129 is 92113412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13337104 + 8094025 = 3652^2 + 2845^2 .

It is a cyclic number.

It is not a de Polignac number, because 21431129 - 2¹⁶ = 21365593 is a prime.

Together with 21431131, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21431119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715564 + 10715565.

It is an arithmetic number, because the mean of its divisors is an integer number (10715565).

Almost surely, 2^21431129 is an apocalyptic number.

It is an amenable number.

21431129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21431129 is an equidigital number, since it uses as much as digits as its factorization.

21431129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 23.

The square root of 21431129 is about 4629.3767399079. The cubic root of 21431129 is about 277.7676620968.

The spelling of 21431129 in words is "twenty-one million, four hundred thirty-one thousand, one hundred twenty-nine".