20783993 has 2 divisors, whose sum is σ = 20783994. Its totient is φ = 20783992.

The previous prime is 20783969. The next prime is 20783999. The reversal of 20783993 is 39938702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14961424 + 5822569 = 3868^2 + 2413^2 .

It is a cyclic number.

It is not a de Polignac number, because 20783993 - 2¹⁰ = 20782969 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20783993.

It is not a weakly prime, because it can be changed into another prime (20783999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10391996 + 10391997.

It is an arithmetic number, because the mean of its divisors is an integer number (10391997).

Almost surely, 2^20783993 is an apocalyptic number.

It is an amenable number.

20783993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20783993 is an equidigital number, since it uses as much as digits as its factorization.

20783993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 81648, while the sum is 41.

The square root of 20783993 is about 4558.9464791770. The cubic root of 20783993 is about 274.9432081071.

The spelling of 20783993 in words is "twenty million, seven hundred eighty-three thousand, nine hundred ninety-three".