20940565957 has 6 divisors (see below), whose sum is σ = 21075770258. Its totient is φ = 20805384912.

The previous prime is 20940565927. The next prime is 20940565963. The reversal of 20940565957 is 75956504902.

It can be written as a sum of positive squares in 3 ways, for example, as 12543776001 + 8396789956 = 111999^2 + 91634^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20940565957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20940565907) 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 5 ways as a sum of consecutive naturals, for example, 1807419 + ... + 1818967.

Almost surely, 2^20940565957 is an apocalyptic number.

It is an amenable number.

20940565957 is a deficient number, since it is larger than the sum of its proper divisors (135204301).

20940565957 is an frugal number, since it uses more digits than its factorization.

20940565957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23255 (or 11706 counting only the distinct ones).

The product of its (nonzero) digits is 3402000, while the sum is 52.

The spelling of 20940565957 in words is "twenty billion, nine hundred forty million, five hundred sixty-five thousand, nine hundred fifty-seven".