20813939 has 4 divisors (see below), whose sum is σ = 20873256. Its totient is φ = 20754624.

The previous prime is 20813929. The next prime is 20813953. The reversal of 20813939 is 93931802.

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 20813939 - 2²⁴ = 4036723 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20813899 and 20813908.

It is not an unprimeable number, because it can be changed into a prime (20813929) 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, 29129 + ... + 29834.

It is an arithmetic number, because the mean of its divisors is an integer number (5218314).

Almost surely, 2^20813939 is an apocalyptic number.

20813939 is a deficient number, since it is larger than the sum of its proper divisors (59317).

20813939 is an equidigital number, since it uses as much as digits as its factorization.

20813939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59316.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 20813939 is about 4562.2296084261. The cubic root of 20813939 is about 275.0751926615.

The spelling of 20813939 in words is "twenty million, eight hundred thirteen thousand, nine hundred thirty-nine".