1261643 has 2 divisors, whose sum is σ = 1261644. Its totient is φ = 1261642.

The previous prime is 1261639. The next prime is 1261649. The reversal of 1261643 is 3461621.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1261643 - 2² = 1261639 is a prime.

It is not a weakly prime, because it can be changed into another prime (1261649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630821 + 630822.

It is an arithmetic number, because the mean of its divisors is an integer number (630822).

2^1261643 is an apocalyptic number.

1261643 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261643 is an equidigital number, since it uses as much as digits as its factorization.

1261643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 23.

The square root of 1261643 is about 1123.2288279776. The cubic root of 1261643 is about 108.0551558690.

Adding to 1261643 its sum of digits (23), we get a triangular number (1261666 = T₁₅₈₈).

The spelling of 1261643 in words is "one million, two hundred sixty-one thousand, six hundred forty-three".