1247687321 has 4 divisors (see below), whose sum is σ = 1255634532. Its totient is φ = 1239740112.

The previous prime is 1247687317. The next prime is 1247687347. The reversal of 1247687321 is 1237867421.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1237867421 = 7 ⋅176838203.

It can be written as a sum of positive squares in 2 ways, for example, as 932447296 + 315240025 = 30536^2 + 17755^2 .

It is a cyclic number.

It is not a de Polignac number, because 1247687321 - 2² = 1247687317 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1247687621) 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, 3973370 + ... + 3973683.

It is an arithmetic number, because the mean of its divisors is an integer number (313908633).

Almost surely, 2^1247687321 is an apocalyptic number.

It is an amenable number.

1247687321 is a deficient number, since it is larger than the sum of its proper divisors (7947211).

1247687321 is an equidigital number, since it uses as much as digits as its factorization.

1247687321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7947210.

The product of its digits is 112896, while the sum is 41.

The square root of 1247687321 is about 35322.6176974471. The cubic root of 1247687321 is about 1076.5525994405.

The spelling of 1247687321 in words is "one billion, two hundred forty-seven million, six hundred eighty-seven thousand, three hundred twenty-one".