20787757477457 has 2 divisors, whose sum is σ = 20787757477458. Its totient is φ = 20787757477456.

The previous prime is 20787757477433. The next prime is 20787757477499. The reversal of 20787757477457 is 75477475778702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20785794012736 + 1963464721 = 4559144^2 + 44311^2 .

It is a cyclic number.

It is not a de Polignac number, because 20787757477457 - 2¹² = 20787757473361 is a prime.

It is not a weakly prime, because it can be changed into another prime (20787757477757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10393878738728 + 10393878738729.

It is an arithmetic number, because the mean of its divisors is an integer number (10393878738729).

Almost surely, 2^{20787757477457} is an apocalyptic number.

It is an amenable number.

20787757477457 is a deficient number, since it is larger than the sum of its proper divisors (1).

20787757477457 is an equidigital number, since it uses as much as digits as its factorization.

20787757477457 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5270675200, while the sum is 77.

The spelling of 20787757477457 in words is "twenty trillion, seven hundred eighty-seven billion, seven hundred fifty-seven million, four hundred seventy-seven thousand, four hundred fifty-seven".