20781841 has 2 divisors, whose sum is σ = 20781842. Its totient is φ = 20781840.

The previous prime is 20781833. The next prime is 20781851. The reversal of 20781841 is 14818702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19580625 + 1201216 = 4425^2 + 1096^2 .

It is a cyclic number.

It is not a de Polignac number, because 20781841 - 2³ = 20781833 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20781851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10390920 + 10390921.

It is an arithmetic number, because the mean of its divisors is an integer number (10390921).

Almost surely, 2^20781841 is an apocalyptic number.

It is an amenable number.

20781841 is a deficient number, since it is larger than the sum of its proper divisors (1).

20781841 is an equidigital number, since it uses as much as digits as its factorization.

20781841 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 20781841 is about 4558.7104536261. The cubic root of 20781841 is about 274.9337184611.

The spelling of 20781841 in words is "twenty million, seven hundred eighty-one thousand, eight hundred forty-one".