398731821 has 16 divisors (see below), whose sum is σ = 563984064. Its totient is φ = 249709824.

The previous prime is 398731799. The next prime is 398731829. The reversal of 398731821 is 128137893.

It is not a de Polignac number, because 398731821 - 2¹³ = 398723629 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398731829) 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, 20751 + ... + 35043.

It is an arithmetic number, because the mean of its divisors is an integer number (35249004).

Almost surely, 2^398731821 is an apocalyptic number.

It is an amenable number.

398731821 is a deficient number, since it is larger than the sum of its proper divisors (165252243).

398731821 is a wasteful number, since it uses less digits than its factorization.

398731821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14860.

The product of its digits is 72576, while the sum is 42.

The square root of 398731821 is about 19968.2703557419. The cubic root of 398731821 is about 736.0268068026.

The spelling of 398731821 in words is "three hundred ninety-eight million, seven hundred thirty-one thousand, eight hundred twenty-one".