20399399 has 4 divisors (see below), whose sum is σ = 20458200. Its totient is φ = 20340600.

The previous prime is 20399389. The next prime is 20399411. The reversal of 20399399 is 99399302.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99399302 = 2 ⋅49699651.

It is a cyclic number.

It is not a de Polignac number, because 20399399 - 2²⁴ = 3622183 is a prime.

It is a super-2 number, since 2×20399399² = 832270959122402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20399359) 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 3 ways as a sum of consecutive naturals, for example, 28877 + ... + 29574.

It is an arithmetic number, because the mean of its divisors is an integer number (5114550).

Almost surely, 2^20399399 is an apocalyptic number.

20399399 is a deficient number, since it is larger than the sum of its proper divisors (58801).

20399399 is an equidigital number, since it uses as much as digits as its factorization.

20399399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58800.

The product of its (nonzero) digits is 118098, while the sum is 44.

The square root of 20399399 is about 4516.5693839462. The cubic root of 20399399 is about 273.2367583003.

The spelling of 20399399 in words is "twenty million, three hundred ninety-nine thousand, three hundred ninety-nine".