1309916021 has 2 divisors, whose sum is σ = 1309916022. Its totient is φ = 1309916020.

The previous prime is 1309915913. The next prime is 1309916071. The reversal of 1309916021 is 1206199031.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1204853521 + 105062500 = 34711^2 + 10250^2 .

It is an emirp because it is prime and its reverse (1206199031) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1309916021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1309916071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 654958010 + 654958011.

It is an arithmetic number, because the mean of its divisors is an integer number (654958011).

Almost surely, 2^1309916021 is an apocalyptic number.

It is an amenable number.

1309916021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1309916021 is an equidigital number, since it uses as much as digits as its factorization.

1309916021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 1309916021 is about 36192.7619973939. The cubic root of 1309916021 is about 1094.1607995679.

The spelling of 1309916021 in words is "one billion, three hundred nine million, nine hundred sixteen thousand, twenty-one".