20787757477957 has 2 divisors, whose sum is σ = 20787757477958. Its totient is φ = 20787757477956.

The previous prime is 20787757477901. The next prime is 20787757477969. The reversal of 20787757477957 is 75977475778702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19556436574756 + 1231320903201 = 4422266^2 + 1109649^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20787757477957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20787757477457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10393878738978 + 10393878738979.

It is an arithmetic number, because the mean of its divisors is an integer number (10393878738979).

Almost surely, 2^{20787757477957} is an apocalyptic number.

It is an amenable number.

20787757477957 is a deficient number, since it is larger than the sum of its proper divisors (1).

20787757477957 is an equidigital number, since it uses as much as digits as its factorization.

20787757477957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11859019200, while the sum is 82.

The spelling of 20787757477957 in words is "twenty trillion, seven hundred eighty-seven billion, seven hundred fifty-seven million, four hundred seventy-seven thousand, nine hundred fifty-seven".