1311646021 has 4 divisors (see below), whose sum is σ = 1499024032. Its totient is φ = 1124268012.

The previous prime is 1311646009. The next prime is 1311646027. The reversal of 1311646021 is 1206461131.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1206461131 = 31 ⋅38918101.

It is not a de Polignac number, because 1311646021 - 2⁵ = 1311645989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311646027) 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 3 ways as a sum of consecutive naturals, for example, 93688995 + ... + 93689008.

It is an arithmetic number, because the mean of its divisors is an integer number (374756008).

Almost surely, 2^1311646021 is an apocalyptic number.

It is an amenable number.

1311646021 is a deficient number, since it is larger than the sum of its proper divisors (187378011).

1311646021 is an equidigital number, since it uses as much as digits as its factorization.

1311646021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187378010.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 1311646021 is about 36216.6539177766. The cubic root of 1311646021 is about 1094.6422720312.

The spelling of 1311646021 in words is "one billion, three hundred eleven million, six hundred forty-six thousand, twenty-one".