20787757477537 has 2 divisors, whose sum is σ = 20787757477538. Its totient is φ = 20787757477536.

The previous prime is 20787757477499. The next prime is 20787757477573. The reversal of 20787757477537 is 73577475778702.

Together with next prime (20787757477573) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18196401244176 + 2591356233361 = 4265724^2 + 1609769^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20787757477537 is a prime.

It is not a weakly prime, because it can be changed into another prime (20787757577537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10393878738768 + 10393878738769.

It is an arithmetic number, because the mean of its divisors is an integer number (10393878738769).

Almost surely, 2^{20787757477537} is an apocalyptic number.

It is an amenable number.

20787757477537 is a deficient number, since it is larger than the sum of its proper divisors (1).

20787757477537 is an equidigital number, since it uses as much as digits as its factorization.

20787757477537 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3953006400, while the sum is 76.

The spelling of 20787757477537 in words is "twenty trillion, seven hundred eighty-seven billion, seven hundred fifty-seven million, four hundred seventy-seven thousand, five hundred thirty-seven".