397578821 has 2 divisors, whose sum is σ = 397578822. Its totient is φ = 397578820.

The previous prime is 397578809. The next prime is 397578827. The reversal of 397578821 is 128875793.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 352876225 + 44702596 = 18785^2 + 6686^2 .

It is a cyclic number.

It is not a de Polignac number, because 397578821 - 2¹⁰ = 397577797 is a prime.

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 397578821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (397578827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198789410 + 198789411.

It is an arithmetic number, because the mean of its divisors is an integer number (198789411).

Almost surely, 2^397578821 is an apocalyptic number.

It is an amenable number.

397578821 is a deficient number, since it is larger than the sum of its proper divisors (1).

397578821 is an equidigital number, since it uses as much as digits as its factorization.

397578821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 846720, while the sum is 50.

The square root of 397578821 is about 19939.3786513021. The cubic root of 397578821 is about 735.3166735133.

The spelling of 397578821 in words is "three hundred ninety-seven million, five hundred seventy-eight thousand, eight hundred twenty-one".