66121313 has 4 divisors (see below), whose sum is σ = 70010820. Its totient is φ = 62231808.

The previous prime is 66121309. The next prime is 66121351. The reversal of 66121313 is 31312166.

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 32341969 + 33779344 = 5687^2 + 5812^2 .

It is a cyclic number.

It is not a de Polignac number, because 66121313 - 2² = 66121309 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66121303) 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, 1944728 + ... + 1944761.

It is an arithmetic number, because the mean of its divisors is an integer number (17502705).

Almost surely, 2^66121313 is an apocalyptic number.

It is an amenable number.

66121313 is a deficient number, since it is larger than the sum of its proper divisors (3889507).

66121313 is a wasteful number, since it uses less digits than its factorization.

66121313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3889506.

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

The square root of 66121313 is about 8131.5012759023. The cubic root of 66121313 is about 404.3714540227.

Adding to 66121313 its reverse (31312166), we get a palindrome (97433479).

The spelling of 66121313 in words is "sixty-six million, one hundred twenty-one thousand, three hundred thirteen".