20400399 has 6 divisors (see below), whose sum is σ = 29467256. Its totient is φ = 13600260.

The previous prime is 20400377. The next prime is 20400421. The reversal of 20400399 is 99300402.

It is an interprime number because it is at equal distance from previous prime (20400377) and next prime (20400421).

It is not a de Polignac number, because 20400399 - 2⁷ = 20400271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20400349) 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 in 5 ways as a sum of consecutive naturals, for example, 1133347 + ... + 1133364.

Almost surely, 2^20400399 is an apocalyptic number.

20400399 is a deficient number, since it is larger than the sum of its proper divisors (9066857).

20400399 is a wasteful number, since it uses less digits than its factorization.

20400399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2266717 (or 2266714 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 20400399 is about 4516.6800860809. The cubic root of 20400399 is about 273.2412230118.

The spelling of 20400399 in words is "twenty million, four hundred thousand, three hundred ninety-nine".