661312013 has 2 divisors, whose sum is σ = 661312014. Its totient is φ = 661312012.

The previous prime is 661311983. The next prime is 661312033. The reversal of 661312013 is 310213166.

It is a happy number.

661312013 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 630863689 + 30448324 = 25117^2 + 5518^2 .

It is a cyclic number.

It is not a de Polignac number, because 661312013 - 2¹² = 661307917 is a prime.

It is a super-2 number, since 2×661312013² = 874667157076224338, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 661312013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661312033) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330656006 + 330656007.

It is an arithmetic number, because the mean of its divisors is an integer number (330656007).

Almost surely, 2^661312013 is an apocalyptic number.

It is an amenable number.

661312013 is a deficient number, since it is larger than the sum of its proper divisors (1).

661312013 is an equidigital number, since it uses as much as digits as its factorization.

661312013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 661312013 is about 25715.9874980526. The cubic root of 661312013 is about 871.2353143308.

Adding to 661312013 its reverse (310213166), we get a palindrome (971525179).

The spelling of 661312013 in words is "six hundred sixty-one million, three hundred twelve thousand, thirteen".