20767921777 has 2 divisors, whose sum is σ = 20767921778. Its totient is φ = 20767921776.

The previous prime is 20767921651. The next prime is 20767921781. The reversal of 20767921777 is 77712976702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13807190016 + 6960731761 = 117504^2 + 83431^2 .

It is a cyclic number.

It is not a de Polignac number, because 20767921777 - 2²³ = 20759533169 is a prime.

It is not a weakly prime, because it can be changed into another prime (20767921787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10383960888 + 10383960889.

It is an arithmetic number, because the mean of its divisors is an integer number (10383960889).

Almost surely, 2^20767921777 is an apocalyptic number.

It is an amenable number.

20767921777 is a deficient number, since it is larger than the sum of its proper divisors (1).

20767921777 is an equidigital number, since it uses as much as digits as its factorization.

20767921777 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3630312, while the sum is 55.

The spelling of 20767921777 in words is "twenty billion, seven hundred sixty-seven million, nine hundred twenty-one thousand, seven hundred seventy-seven".