20787757477821 has 8 divisors (see below), whose sum is σ = 30796677744960. Its totient is φ = 13858504985196.

The previous prime is 20787757477763. The next prime is 20787757477843. The reversal of 20787757477821 is 12877475778702.

20787757477821 is a `hidden beast` number, since 2 + 0 + 7 + 8 + 7 + 75 + 7 + 477 + 82 + 1 = 666.

It is not a de Polignac number, because 20787757477821 - 2⁶ = 20787757477757 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20787757477821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20787757477871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384958471785 + ... + 384958471838.

It is an arithmetic number, because the mean of its divisors is an integer number (3849584718120).

Almost surely, 2^{20787757477821} is an apocalyptic number.

It is an amenable number.

20787757477821 is a deficient number, since it is larger than the sum of its proper divisors (10008920267139).

20787757477821 is an equidigital number, since it uses as much as digits as its factorization.

20787757477821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 769916943632 (or 769916943626 counting only the distinct ones).

The product of its (nonzero) digits is 602362880, while the sum is 72.

The spelling of 20787757477821 in words is "twenty trillion, seven hundred eighty-seven billion, seven hundred fifty-seven million, four hundred seventy-seven thousand, eight hundred twenty-one".