20399969 has 2 divisors, whose sum is σ = 20399970. Its totient is φ = 20399968.

The previous prime is 20399947. The next prime is 20399993. The reversal of 20399969 is 96999302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19891600 + 508369 = 4460^2 + 713^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20399969 is a prime.

It is a super-2 number, since 2×20399969² = 832317470401922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20399909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10199984 + 10199985.

It is an arithmetic number, because the mean of its divisors is an integer number (10199985).

Almost surely, 2^20399969 is an apocalyptic number.

It is an amenable number.

20399969 is a deficient number, since it is larger than the sum of its proper divisors (1).

20399969 is an equidigital number, since it uses as much as digits as its factorization.

20399969 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 236196, while the sum is 47.

The square root of 20399969 is about 4516.6324844955. The cubic root of 20399969 is about 273.2393032038.

The spelling of 20399969 in words is "twenty million, three hundred ninety-nine thousand, nine hundred sixty-nine".