20506783 has 4 divisors (see below), whose sum is σ = 22371048. Its totient is φ = 18642520.

The previous prime is 20506781. The next prime is 20506789. The reversal of 20506783 is 38760502.

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 20506783 - 2¹ = 20506781 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20506781) 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, 932116 + ... + 932137.

It is an arithmetic number, because the mean of its divisors is an integer number (5592762).

Almost surely, 2^20506783 is an apocalyptic number.

20506783 is a deficient number, since it is larger than the sum of its proper divisors (1864265).

20506783 is a wasteful number, since it uses less digits than its factorization.

20506783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1864264.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 20506783 is about 4528.4415641587. The cubic root of 20506783 is about 273.7153658845.

The spelling of 20506783 in words is "twenty million, five hundred six thousand, seven hundred eighty-three".