20390939 has 4 divisors (see below), whose sum is σ = 21590424. Its totient is φ = 19191456.

The previous prime is 20390911. The next prime is 20390941. The reversal of 20390939 is 93909302.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20390939 - 2¹² = 20386843 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20390899 and 20390908.

It is not an unprimeable number, because it can be changed into a prime (20390039) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 599717 + ... + 599750.

It is an arithmetic number, because the mean of its divisors is an integer number (5397606).

Almost surely, 2^20390939 is an apocalyptic number.

20390939 is a deficient number, since it is larger than the sum of its proper divisors (1199485).

20390939 is a wasteful number, since it uses less digits than its factorization.

20390939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1199484.

The product of its (nonzero) digits is 13122, while the sum is 35.

The square root of 20390939 is about 4515.6327352875. The cubic root of 20390939 is about 273.1989810011.

The spelling of 20390939 in words is "twenty million, three hundred ninety thousand, nine hundred thirty-nine".