1646431321 has 4 divisors (see below), whose sum is σ = 1646722000. Its totient is φ = 1646140644.

The previous prime is 1646431313. The next prime is 1646431327. The reversal of 1646431321 is 1231346461.

It is a happy number.

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 1646431321 - 2³ = 1646431313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1646431327) 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, 136671 + ... + 148228.

It is an arithmetic number, because the mean of its divisors is an integer number (411680500).

Almost surely, 2^1646431321 is an apocalyptic number.

It is an amenable number.

1646431321 is a deficient number, since it is larger than the sum of its proper divisors (290679).

1646431321 is an equidigital number, since it uses as much as digits as its factorization.

1646431321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290678.

The product of its digits is 10368, while the sum is 31.

The square root of 1646431321 is about 40576.2408436267. The cubic root of 1646431321 is about 1180.8132192306.

Adding to 1646431321 its reverse (1231346461), we get a palindrome (2877777782).

The spelling of 1646431321 in words is "one billion, six hundred forty-six million, four hundred thirty-one thousand, three hundred twenty-one".