396447921 has 9 divisors (see below), whose sum is σ = 572733291. Its totient is φ = 264258792.

The previous prime is 396447913. The next prime is 396447929. The reversal of 396447921 is 129744693.

It is a happy number.

The square root of 396447921 is 19911.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (396447913) and next prime (396447929).

It can be written as a sum of positive squares in only one way, i.e., 5832225 + 390615696 = 2415^2 + 19764^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 396447921 - 2³ = 396447913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (396447929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 56415 + ... + 63051.

Almost surely, 2^396447921 is an apocalyptic number.

396447921 is the 19911-st square number.

396447921 is the 9956-th centered octagonal number.

It is an amenable number.

396447921 is a deficient number, since it is larger than the sum of its proper divisors (176285370).

396447921 is an frugal number, since it uses more digits than its factorization.

396447921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13280 (or 6640 counting only the distinct ones).

The product of its digits is 326592, while the sum is 45.

The cubic root of 396447921 is about 734.6188166457.

The spelling of 396447921 in words is "three hundred ninety-six million, four hundred forty-seven thousand, nine hundred twenty-one".