1261310621 has 2 divisors, whose sum is σ = 1261310622. Its totient is φ = 1261310620.

The previous prime is 1261310591. The next prime is 1261310629. The reversal of 1261310621 is 1260131621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1220733721 + 40576900 = 34939^2 + 6370^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261310621 - 2¹⁰ = 1261309597 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1261310629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630655310 + 630655311.

It is an arithmetic number, because the mean of its divisors is an integer number (630655311).

Almost surely, 2^1261310621 is an apocalyptic number.

It is an amenable number.

1261310621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261310621 is an equidigital number, since it uses as much as digits as its factorization.

1261310621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1261310621 is about 35514.9351822582. The cubic root of 1261310621 is about 1080.4566601623.

The spelling of 1261310621 in words is "one billion, two hundred sixty-one million, three hundred ten thousand, six hundred twenty-one".