1286847721 has 2 divisors, whose sum is σ = 1286847722. Its totient is φ = 1286847720.

The previous prime is 1286847719. The next prime is 1286847739. The reversal of 1286847721 is 1277486821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1089726121 + 197121600 = 33011^2 + 14040^2 .

It is a cyclic number.

It is not a de Polignac number, because 1286847721 - 2¹ = 1286847719 is a prime.

Together with 1286847719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1286847781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 643423860 + 643423861.

It is an arithmetic number, because the mean of its divisors is an integer number (643423861).

Almost surely, 2^1286847721 is an apocalyptic number.

It is an amenable number.

1286847721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1286847721 is an equidigital number, since it uses as much as digits as its factorization.

1286847721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 301056, while the sum is 46.

The square root of 1286847721 is about 35872.6597982363. The cubic root of 1286847721 is about 1087.6998097827.

The spelling of 1286847721 in words is "one billion, two hundred eighty-six million, eight hundred forty-seven thousand, seven hundred twenty-one".