21115429 has 2 divisors, whose sum is σ = 21115430. Its totient is φ = 21115428.

The previous prime is 21115427. The next prime is 21115439. The reversal of 21115429 is 92451112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18507204 + 2608225 = 4302^2 + 1615^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115429 - 2¹ = 21115427 is a prime.

It is a super-2 number, since 2×21115429² = 891722683708082, which contains 22 as substring.

Together with 21115427, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21115421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10557714 + 10557715.

It is an arithmetic number, because the mean of its divisors is an integer number (10557715).

Almost surely, 2^21115429 is an apocalyptic number.

It is an amenable number.

21115429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21115429 is an equidigital number, since it uses as much as digits as its factorization.

21115429 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 25.

The square root of 21115429 is about 4595.1527722155. The cubic root of 21115429 is about 276.3969861299.

The spelling of 21115429 in words is "twenty-one million, one hundred fifteen thousand, four hundred twenty-nine".