397793821 has 2 divisors, whose sum is σ = 397793822. Its totient is φ = 397793820.

The previous prime is 397793819. The next prime is 397793831. The reversal of 397793821 is 128397793.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 338964921 + 58828900 = 18411^2 + 7670^2 .

It is an emirp because it is prime and its reverse (128397793) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 397793821 - 2¹ = 397793819 is a prime.

Together with 397793819, 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 (397793801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198896910 + 198896911.

It is an arithmetic number, because the mean of its divisors is an integer number (198896911).

Almost surely, 2^397793821 is an apocalyptic number.

It is an amenable number.

397793821 is a deficient number, since it is larger than the sum of its proper divisors (1).

397793821 is an equidigital number, since it uses as much as digits as its factorization.

397793821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 571536, while the sum is 49.

The square root of 397793821 is about 19944.7692641454. The cubic root of 397793821 is about 735.4491961625.

The spelling of 397793821 in words is "three hundred ninety-seven million, seven hundred ninety-three thousand, eight hundred twenty-one".