21234709 has 2 divisors, whose sum is σ = 21234710. Its totient is φ = 21234708.

The previous prime is 21234701. The next prime is 21234713. The reversal of 21234709 is 90743212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19847025 + 1387684 = 4455^2 + 1178^2 .

It is a cyclic number.

It is not a de Polignac number, because 21234709 - 2³ = 21234701 is a prime.

It is a Chen prime.

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

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21234701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10617354 + 10617355.

It is an arithmetic number, because the mean of its divisors is an integer number (10617355).

Almost surely, 2^21234709 is an apocalyptic number.

It is an amenable number.

21234709 is a deficient number, since it is larger than the sum of its proper divisors (1).

21234709 is an equidigital number, since it uses as much as digits as its factorization.

21234709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 21234709 is about 4608.1133883619. The cubic root of 21234709 is about 276.9164601003.

The spelling of 21234709 in words is "twenty-one million, two hundred thirty-four thousand, seven hundred nine".