21368429 has 2 divisors, whose sum is σ = 21368430. Its totient is φ = 21368428.

The previous prime is 21368401. The next prime is 21368453. The reversal of 21368429 is 92486312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10903204 + 10465225 = 3302^2 + 3235^2 .

It is a cyclic number.

It is not a de Polignac number, because 21368429 - 2¹² = 21364333 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21368489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684214 + 10684215.

It is an arithmetic number, because the mean of its divisors is an integer number (10684215).

Almost surely, 2^21368429 is an apocalyptic number.

It is an amenable number.

21368429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21368429 is an equidigital number, since it uses as much as digits as its factorization.

21368429 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20736, while the sum is 35.

The square root of 21368429 is about 4622.5998096309. The cubic root of 21368429 is about 277.4965137673.

The spelling of 21368429 in words is "twenty-one million, three hundred sixty-eight thousand, four hundred twenty-nine".