20747664649 has 2 divisors, whose sum is σ = 20747664650. Its totient is φ = 20747664648.

The previous prime is 20747664551. The next prime is 20747664653. The reversal of 20747664649 is 94646674702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20709224649 + 38440000 = 143907^2 + 6200^2 .

It is a cyclic number.

It is not a de Polignac number, because 20747664649 - 2¹⁷ = 20747533577 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20747664649.

It is not a weakly prime, because it can be changed into another prime (20747665649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10373832324 + 10373832325.

It is an arithmetic number, because the mean of its divisors is an integer number (10373832325).

Almost surely, 2^20747664649 is an apocalyptic number.

It is an amenable number.

20747664649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20747664649 is an equidigital number, since it uses as much as digits as its factorization.

20747664649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12192768, while the sum is 55.

The spelling of 20747664649 in words is "twenty billion, seven hundred forty-seven million, six hundred sixty-four thousand, six hundred forty-nine".