1311011021 has 4 divisors (see below), whose sum is σ = 1335747132. Its totient is φ = 1286274912.

The previous prime is 1311011003. The next prime is 1311011069. The reversal of 1311011021 is 1201101131.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 324360100 + 986650921 = 18010^2 + 31411^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1311011021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1311010993 and 1311011011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1311011071) 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, 12367976 + ... + 12368081.

It is an arithmetic number, because the mean of its divisors is an integer number (333936783).

Almost surely, 2^1311011021 is an apocalyptic number.

It is an amenable number.

1311011021 is a deficient number, since it is larger than the sum of its proper divisors (24736111).

1311011021 is an equidigital number, since it uses as much as digits as its factorization.

1311011021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24736110.

The product of its (nonzero) digits is 6, while the sum is 11.

The square root of 1311011021 is about 36207.8861713854. The cubic root of 1311011021 is about 1094.4655957956.

Adding to 1311011021 its reverse (1201101131), we get a palindrome (2512112152).

The spelling of 1311011021 in words is "one billion, three hundred eleven million, eleven thousand, twenty-one".