20440309 has 2 divisors, whose sum is σ = 20440310. Its totient is φ = 20440308.

The previous prime is 20440297. The next prime is 20440313. The reversal of 20440309 is 90304402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19624900 + 815409 = 4430^2 + 903^2 .

It is a cyclic number.

It is not a de Polignac number, because 20440309 - 2¹³ = 20432117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20440309.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20440319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10220154 + 10220155.

It is an arithmetic number, because the mean of its divisors is an integer number (10220155).

Almost surely, 2^20440309 is an apocalyptic number.

It is an amenable number.

20440309 is a deficient number, since it is larger than the sum of its proper divisors (1).

20440309 is an equidigital number, since it uses as much as digits as its factorization.

20440309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 20440309 is about 4521.0959954418. The cubic root of 20440309 is about 273.4192906666.

The spelling of 20440309 in words is "twenty million, four hundred forty thousand, three hundred nine".