4194947821 has 2 divisors, whose sum is σ = 4194947822. Its totient is φ = 4194947820.

The previous prime is 4194947819. The next prime is 4194947873. The reversal of 4194947821 is 1287494914.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2674337796 + 1520610025 = 51714^2 + 38995^2 .

It is a cyclic number.

It is not a de Polignac number, because 4194947821 - 2¹ = 4194947819 is a prime.

Together with 4194947819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4194947891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2097473910 + 2097473911.

It is an arithmetic number, because the mean of its divisors is an integer number (2097473911).

Almost surely, 2^4194947821 is an apocalyptic number.

It is an amenable number.

4194947821 is a deficient number, since it is larger than the sum of its proper divisors (1).

4194947821 is an equidigital number, since it uses as much as digits as its factorization.

4194947821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 580608, while the sum is 49.

The square root of 4194947821 is about 64768.4168480286. The cubic root of 4194947821 is about 1612.7814554753.

The spelling of 4194947821 in words is "four billion, one hundred ninety-four million, nine hundred forty-seven thousand, eight hundred twenty-one".