3777220721 has 2 divisors, whose sum is σ = 3777220722. Its totient is φ = 3777220720.

The previous prime is 3777220697. The next prime is 3777220723. The reversal of 3777220721 is 1270227773.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2802220096 + 975000625 = 52936^2 + 31225^2 .

It is a cyclic number.

It is not a de Polignac number, because 3777220721 - 2¹⁰ = 3777219697 is a prime.

Together with 3777220723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (3777220723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1888610360 + 1888610361.

It is an arithmetic number, because the mean of its divisors is an integer number (1888610361).

Almost surely, 2^3777220721 is an apocalyptic number.

It is an amenable number.

3777220721 is a deficient number, since it is larger than the sum of its proper divisors (1).

3777220721 is an equidigital number, since it uses as much as digits as its factorization.

3777220721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 57624, while the sum is 38.

The square root of 3777220721 is about 61459.0979514018. The cubic root of 3777220721 is about 1557.3663541480.

The spelling of 3777220721 in words is "three billion, seven hundred seventy-seven million, two hundred twenty thousand, seven hundred twenty-one".