1243213666 has 4 divisors (see below), whose sum is σ = 1864820502. Its totient is φ = 621606832.

The previous prime is 1243213663. The next prime is 1243213679. The reversal of 1243213666 is 6663123421.

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

It can be written as a sum of positive squares in only one way, i.e., 623950441 + 619263225 = 24979^2 + 24885^2 .

It is not an unprimeable number, because it can be changed into a prime (1243213663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310803415 + ... + 310803418.

Almost surely, 2^1243213666 is an apocalyptic number.

1243213666 is a deficient number, since it is larger than the sum of its proper divisors (621606836).

1243213666 is an equidigital number, since it uses as much as digits as its factorization.

1243213666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621606835.

The product of its digits is 31104, while the sum is 34.

The square root of 1243213666 is about 35259.2351873945. The cubic root of 1243213666 is about 1075.2643780257.

The spelling of 1243213666 in words is "one billion, two hundred forty-three million, two hundred thirteen thousand, six hundred sixty-six".