321240021 has 16 divisors (see below), whose sum is σ = 431193600. Its totient is φ = 212729328.

The previous prime is 321240019. The next prime is 321240037. The reversal of 321240021 is 120042123.

It is not a de Polignac number, because 321240021 - 2¹ = 321240019 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 (321240421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 407790 + ... + 408576.

It is an arithmetic number, because the mean of its divisors is an integer number (26949600).

Almost surely, 2^321240021 is an apocalyptic number.

It is an amenable number.

321240021 is a deficient number, since it is larger than the sum of its proper divisors (109953579).

321240021 is a wasteful number, since it uses less digits than its factorization.

321240021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1528.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 321240021 is about 17923.1699484215. The cubic root of 321240021 is about 684.8727424458.

Adding to 321240021 its reverse (120042123), we get a palindrome (441282144).

The spelling of 321240021 in words is "three hundred twenty-one million, two hundred forty thousand, twenty-one".