20981783 has 2 divisors, whose sum is σ = 20981784. Its totient is φ = 20981782.

The previous prime is 20981767. The next prime is 20981789. The reversal of 20981783 is 38718902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20981783 - 2⁴ = 20981767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20981789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10490891 + 10490892.

It is an arithmetic number, because the mean of its divisors is an integer number (10490892).

Almost surely, 2^20981783 is an apocalyptic number.

20981783 is a deficient number, since it is larger than the sum of its proper divisors (1).

20981783 is an equidigital number, since it uses as much as digits as its factorization.

20981783 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 20981783 is about 4580.5876260585. The cubic root of 20981783 is about 275.8126178577.

The spelling of 20981783 in words is "twenty million, nine hundred eighty-one thousand, seven hundred eighty-three".