21192709 has 2 divisors, whose sum is σ = 21192710. Its totient is φ = 21192708.

The previous prime is 21192671. The next prime is 21192713. The reversal of 21192709 is 90729112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 124609 = 4590^2 + 353^2 .

It is a cyclic number.

It is not a de Polignac number, because 21192709 - 2¹¹ = 21190661 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 (21199709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10596354 + 10596355.

It is an arithmetic number, because the mean of its divisors is an integer number (10596355).

Almost surely, 2^21192709 is an apocalyptic number.

It is an amenable number.

21192709 is a deficient number, since it is larger than the sum of its proper divisors (1).

21192709 is an equidigital number, since it uses as much as digits as its factorization.

21192709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 31.

The square root of 21192709 is about 4603.5539531975. The cubic root of 21192709 is about 276.7337691465.

The spelling of 21192709 in words is "twenty-one million, one hundred ninety-two thousand, seven hundred nine".