20506766641 has 2 divisors, whose sum is σ = 20506766642. Its totient is φ = 20506766640.

The previous prime is 20506766639. The next prime is 20506766653. The reversal of 20506766641 is 14666760502.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20501944225 + 4822416 = 143185^2 + 2196^2 .

It is a cyclic number.

It is not a de Polignac number, because 20506766641 - 2¹ = 20506766639 is a prime.

It is a super-3 number, since 3×20506766641³ (a number of 32 digits) contains 333 as substring.

Together with 20506766639, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20506766741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10253383320 + 10253383321.

It is an arithmetic number, because the mean of its divisors is an integer number (10253383321).

Almost surely, 2^20506766641 is an apocalyptic number.

It is an amenable number.

20506766641 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506766641 is an equidigital number, since it uses as much as digits as its factorization.

20506766641 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 43.

The spelling of 20506766641 in words is "twenty billion, five hundred six million, seven hundred sixty-six thousand, six hundred forty-one".