20787757477787 has 4 divisors (see below), whose sum is σ = 20796488163696. Its totient is φ = 20779026791880.

The previous prime is 20787757477763. The next prime is 20787757477843. The reversal of 20787757477787 is 78777475778702.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20787757477787 - 2⁶ = 20787757477723 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20787757477757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4365339383 + ... + 4365344144.

It is an arithmetic number, because the mean of its divisors is an integer number (5199122040924).

Almost surely, 2^{20787757477787} is an apocalyptic number.

20787757477787 is a deficient number, since it is larger than the sum of its proper divisors (8730685909).

20787757477787 is an equidigital number, since it uses as much as digits as its factorization.

20787757477787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8730685908.

The product of its (nonzero) digits is 14757890560, while the sum is 83.

The spelling of 20787757477787 in words is "twenty trillion, seven hundred eighty-seven billion, seven hundred fifty-seven million, four hundred seventy-seven thousand, seven hundred eighty-seven".