397756821 has 16 divisors (see below), whose sum is σ = 661206528. Its totient is φ = 206626800.

The previous prime is 397756789. The next prime is 397756829. The reversal of 397756821 is 128657793.

It is not a de Polignac number, because 397756821 - 2⁵ = 397756789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (397756829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 860715 + ... + 861176.

It is an arithmetic number, because the mean of its divisors is an integer number (41325408).

Almost surely, 2^397756821 is an apocalyptic number.

It is an amenable number.

397756821 is a deficient number, since it is larger than the sum of its proper divisors (263449707).

397756821 is a wasteful number, since it uses less digits than its factorization.

397756821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1721912.

The product of its digits is 635040, while the sum is 48.

The square root of 397756821 is about 19943.8416810804. The cubic root of 397756821 is about 735.4263933414.

The spelling of 397756821 in words is "three hundred ninety-seven million, seven hundred fifty-six thousand, eight hundred twenty-one".