20749578673 has 12 divisors (see below), whose sum is σ = 20987499484. Its totient is φ = 20514312000.

The previous prime is 20749578649. The next prime is 20749578679. The reversal of 20749578673 is 37687594702.

It can be written as a sum of positive squares in 6 ways, for example, as 5520044209 + 15229534464 = 74297^2 + 123408^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20749578673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20749578679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11148763 + ... + 11150623.

Almost surely, 2^20749578673 is an apocalyptic number.

It is an amenable number.

20749578673 is a deficient number, since it is larger than the sum of its proper divisors (237920811).

20749578673 is a wasteful number, since it uses less digits than its factorization.

20749578673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3156 (or 3055 counting only the distinct ones).

The product of its (nonzero) digits is 17781120, while the sum is 58.

The spelling of 20749578673 in words is "twenty billion, seven hundred forty-nine million, five hundred seventy-eight thousand, six hundred seventy-three".