20685974399 has 2 divisors, whose sum is σ = 20685974400. Its totient is φ = 20685974398.

The previous prime is 20685974389. The next prime is 20685974411. The reversal of 20685974399 is 99347958602.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20685974399 - 2²⁴ = 20669197183 is a prime.

It is a super-2 number, since 2×20685974399² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20685974389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10342987199 + 10342987200.

It is an arithmetic number, because the mean of its divisors is an integer number (10342987200).

Almost surely, 2^20685974399 is an apocalyptic number.

20685974399 is a deficient number, since it is larger than the sum of its proper divisors (1).

20685974399 is an equidigital number, since it uses as much as digits as its factorization.

20685974399 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 29393280, while the sum is 62.

The spelling of 20685974399 in words is "twenty billion, six hundred eighty-five million, nine hundred seventy-four thousand, three hundred ninety-nine".