21254729 has 2 divisors, whose sum is σ = 21254730. Its totient is φ = 21254728.

The previous prime is 21254707. The next prime is 21254789. The reversal of 21254729 is 92745212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19123129 + 2131600 = 4373^2 + 1460^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21254729 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21254695 and 21254704.

It is not a weakly prime, because it can be changed into another prime (21254789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627364 + 10627365.

It is an arithmetic number, because the mean of its divisors is an integer number (10627365).

Almost surely, 2^21254729 is an apocalyptic number.

It is an amenable number.

21254729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21254729 is an equidigital number, since it uses as much as digits as its factorization.

21254729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 32.

The square root of 21254729 is about 4610.2851321800. The cubic root of 21254729 is about 277.0034580148.

The spelling of 21254729 in words is "twenty-one million, two hundred fifty-four thousand, seven hundred twenty-nine".