20398909 has 2 divisors, whose sum is σ = 20398910. Its totient is φ = 20398908.

The previous prime is 20398897. The next prime is 20398921. The reversal of 20398909 is 90989302.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (20398897) and next prime (20398921).

It can be written as a sum of positive squares in only one way, i.e., 14273284 + 6125625 = 3778^2 + 2475^2 .

It is a cyclic number.

It is not a de Polignac number, because 20398909 - 2¹³ = 20390717 is a prime.

It is a super-2 number, since 2×20398909² = 832230976780562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20398979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10199454 + 10199455.

It is an arithmetic number, because the mean of its divisors is an integer number (10199455).

Almost surely, 2^20398909 is an apocalyptic number.

It is an amenable number.

20398909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20398909 is an equidigital number, since it uses as much as digits as its factorization.

20398909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 20398909 is about 4516.5151389096. The cubic root of 20398909 is about 273.2345705384.

The spelling of 20398909 in words is "twenty million, three hundred ninety-eight thousand, nine hundred nine".