397142821 has 4 divisors (see below), whose sum is σ = 397203232. Its totient is φ = 397082412.

The previous prime is 397142819. The next prime is 397142857. The reversal of 397142821 is 128241793.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 397142821 - 2¹ = 397142819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (397142021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18945 + ... + 33958.

It is an arithmetic number, because the mean of its divisors is an integer number (99300808).

Almost surely, 2^397142821 is an apocalyptic number.

It is an amenable number.

397142821 is a deficient number, since it is larger than the sum of its proper divisors (60411).

397142821 is an equidigital number, since it uses as much as digits as its factorization.

397142821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60410.

The product of its digits is 24192, while the sum is 37.

The square root of 397142821 is about 19928.4425131519. The cubic root of 397142821 is about 735.0477831554.

The spelling of 397142821 in words is "three hundred ninety-seven million, one hundred forty-two thousand, eight hundred twenty-one".