20516939 has 2 divisors, whose sum is σ = 20516940. Its totient is φ = 20516938.

The previous prime is 20516911. The next prime is 20516953. The reversal of 20516939 is 93961502.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20516939 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20516899 and 20516908.

It is not a weakly prime, because it can be changed into another prime (20516999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10258469 + 10258470.

It is an arithmetic number, because the mean of its divisors is an integer number (10258470).

Almost surely, 2^20516939 is an apocalyptic number.

20516939 is a deficient number, since it is larger than the sum of its proper divisors (1).

20516939 is an equidigital number, since it uses as much as digits as its factorization.

20516939 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14580, while the sum is 35.

The square root of 20516939 is about 4529.5627824328. The cubic root of 20516939 is about 273.7605443420.

The spelling of 20516939 in words is "twenty million, five hundred sixteen thousand, nine hundred thirty-nine".