20721763 has 2 divisors, whose sum is σ = 20721764. Its totient is φ = 20721762.

The previous prime is 20721749. The next prime is 20721787. The reversal of 20721763 is 36712702.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20721763 - 2²¹ = 18624611 is a prime.

It is not a weakly prime, because it can be changed into another prime (20721713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10360881 + 10360882.

It is an arithmetic number, because the mean of its divisors is an integer number (10360882).

Almost surely, 2^20721763 is an apocalyptic number.

20721763 is a deficient number, since it is larger than the sum of its proper divisors (1).

20721763 is an equidigital number, since it uses as much as digits as its factorization.

20721763 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3528, while the sum is 28.

The square root of 20721763 is about 4552.1163210094. The cubic root of 20721763 is about 274.6685284446.

The spelling of 20721763 in words is "twenty million, seven hundred twenty-one thousand, seven hundred sixty-three".