4778138021 has 2 divisors, whose sum is σ = 4778138022. Its totient is φ = 4778138020.

The previous prime is 4778138009. The next prime is 4778138023. The reversal of 4778138021 is 1208318774.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4594941796 + 183196225 = 67786^2 + 13535^2 .

It is a cyclic number.

It is not a de Polignac number, because 4778138021 - 2⁶ = 4778137957 is a prime.

Together with 4778138023, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 4778138021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4778138023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2389069010 + 2389069011.

It is an arithmetic number, because the mean of its divisors is an integer number (2389069011).

Almost surely, 2^4778138021 is an apocalyptic number.

It is an amenable number.

4778138021 is a deficient number, since it is larger than the sum of its proper divisors (1).

4778138021 is an equidigital number, since it uses as much as digits as its factorization.

4778138021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 75264, while the sum is 41.

The square root of 4778138021 is about 69124.0769992627. The cubic root of 4778138021 is about 1684.3004455493.

The spelling of 4778138021 in words is "four billion, seven hundred seventy-eight million, one hundred thirty-eight thousand, twenty-one".