1267947721 has 2 divisors, whose sum is σ = 1267947722. Its totient is φ = 1267947720.

The previous prime is 1267947697. The next prime is 1267947727. The reversal of 1267947721 is 1277497621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 988222096 + 279725625 = 31436^2 + 16725^2 .

It is a cyclic number.

It is not a de Polignac number, because 1267947721 - 2⁵ = 1267947689 is a prime.

It is not a weakly prime, because it can be changed into another prime (1267947727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633973860 + 633973861.

It is an arithmetic number, because the mean of its divisors is an integer number (633973861).

Almost surely, 2^1267947721 is an apocalyptic number.

It is an amenable number.

1267947721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1267947721 is an equidigital number, since it uses as much as digits as its factorization.

1267947721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 296352, while the sum is 46.

The square root of 1267947721 is about 35608.2535516697. The cubic root of 1267947721 is about 1082.3484905480.

The spelling of 1267947721 in words is "one billion, two hundred sixty-seven million, nine hundred forty-seven thousand, seven hundred twenty-one".